Chahinian H

References (18)

Title : Non-lipolytic and lipolytic sequence-related carboxylesterases: a comparative study of the structure-function relationships of rabbit liver esterase 1 and bovine pancreatic bile-salt-activated lipase - Chahinian_2010_Biochim.Biophys.Acta_1801_1195
Author(s) : Chahinian H , Fantini J , Garmy N , Manco G , Sarda L
Ref : Biochimica & Biophysica Acta , 1801 :1195 , 2010
Abstract : To differentiate esterases from lipases at the structure-function level, we have compared the kinetic properties and structural features of sequence-related esterase 1 from rabbit liver (rLE) and bile-salt-activated lipase from bovine pancreas (bBAL). In contrast to rLE, bBAL hydrolyses water-insoluble medium and long chain esters as vinyl laurate, trioctanoin and olive oil. Conversely, rLE and bBAL are both active on water-soluble short chain esters as vinyl acetate, vinyl propionate, vinyl butyrate, tripropionin, tributyrin and p-nitrophenyl butyrate. However, the enzymes show distinctive kinetic behaviours. rLE displays maximal activity at low substrate concentration, below the critical micelle concentration, whereas bBAL acts preferencially on emulsified esters, at concentration exceeding the solubility limit. Comparison of the 3D structures of rLE and bBAL shows, in particular, that the peptide loop at positions 116-123 in bBAL is deleted in rLE. This peptide segment interacts with a bile salt molecule thus inducing a conformational transition which gives access to the active site. Inhibition studies and manual docking of a bulky ester molecule as vinyl laurate in the catalytic pocket of rLE and bBAL show that the inability of the esterase to hydrolyse large water-insoluble esters is not due to steric hindrance. It is hypothesized that esterases lack specific hydrophobic structures involved both in the stabilization of the lipase-lipid adsorption complex at interfaces and in the spontaneous transfer of a single substrate molecule from interface to the catalytic site.
ESTHER : Chahinian_2010_Biochim.Biophys.Acta_1801_1195
PubMedSearch : Chahinian_2010_Biochim.Biophys.Acta_1801_1195
PubMedID: 20655391

Title : Distinction between esterases and lipases: comparative biochemical properties of sequence-related carboxylesterases - Chahinian_2009_Protein.Pept.Lett_16_1149
Author(s) : Chahinian H , Sarda L
Ref : Protein Pept Lett , 16 :1149 , 2009
Abstract : Carboxylesterases (Carboxyl ester hydrolase) include two groups of enzymes, namely non-specific esterases (EC and lipases (EC which have been early differentiated on the basis of their substrate specificity. Esterases hydrolyse solutions of water-soluble short acyl chain esters and are inactive against water-insoluble long chain triacylglycerols which, in turn, are specifically hydrolyzed by lipases. Based on the comparison of the primary structures, three families of sequence-related carboxylesterases, namely the lipoprotein lipase family (L-family), the hormonesensitive lipase family (H-family) and the cholinesterase family (C-family) have been identified. Using solutions and emulsions of vinyl, glyceryl and p-nitrophenyl esters, we have reinvestigated the kinetic properties of some esterases and lipases of the H- and C-families. Results indicate that esterases and lipases, which are both active on soluble esters, can be differentiated by their value of Km. Moreover, esterase, unlike lipases, are inactive against water-insoluble esters as vinyl laurate and trioctanoylglycerol. From the the comparison of structural features of sequence-related esterases and lipases, it appears that lipases, unlike esterases, display a significant difference in the distribution of hydrophobic amino acid residues at vicinity of their active site. This observation supports the hypothesis of the existence in lipases of a particular surface domain that specifically interacts with lipid-water interfaces and contributes to the transfer a single substrate molecule from the organized lipid-water interface (supersubstrate) to the catalytic site of the enzyme.
ESTHER : Chahinian_2009_Protein.Pept.Lett_16_1149
PubMedSearch : Chahinian_2009_Protein.Pept.Lett_16_1149
PubMedID: 19508178

Title : Characterization of an exported monoglyceride lipase from Mycobacterium tuberculosis possibly involved in the metabolism of host cell membrane lipids - Cotes_2007_Biochem.J_408_417
Author(s) : Cotes K , Dhouib R , Douchet I , Chahinian H , de Caro A , Carriere F , Canaan S
Ref : Biochemical Journal , 408 :417 , 2007
Abstract : The Rv0183 gene of the Mycobacterium tuberculosis H37Rv strain, which has been implicated as a lysophospholipase, was cloned and expressed in Escherichia coli. The purified Rv0183 protein did not show any activity when lysophospholipid substrates were used, but preferentially hydrolysed monoacylglycerol substrates with a specific activity of 290 units x mg(-1) at 37 degrees C. Rv0183 hydrolyses both long chain di- and triacylglycerols, as determined using the monomolecular film technique, although the turnover was lower than with MAG (monoacyl-glycerol). The enzyme shows an optimum activity at pH values ranging from 7.5 to 9.0 using mono-olein as substrate and is inactivated by serine esterase inhibitors such as E600, PMSF and tetrahydrolipstatin. The catalytic triad is composed of Ser110, Asp226 and His256 residues, as confirmed by the results of site-directed mutagenesis. Rv0183 shows 35% sequence identity with the human and mouse monoglyceride lipases and well below 15% with the other bacterial lipases characterized so far. Homologues of Rv0183 can be identified in other mycobacterial genomes such as Mycobacterium bovis, Mycobacterium smegmatis, and even Mycobacterium leprae, which is known to contain a low number of genes involved in the replication process within the host cells. The results of immunolocalization studies performed with polyclonal antibodies raised against the purified recombinant Rv0183 suggested that the enzyme was present only in the cell wall and culture medium of M. tuberculosis. Our results identify Rv0183 as the first exported lipolytic enzyme to be characterized in M. tuberculosis and suggest that Rv0183 may be involved in the degradation of the host cell lipids.
ESTHER : Cotes_2007_Biochem.J_408_417
PubMedSearch : Cotes_2007_Biochem.J_408_417
PubMedID: 17784850
Gene_locus related to this paper: myctu-rv0183

Title : How gastric lipase, an interfacial enzyme with a Ser-His-Asp catalytic triad, acts optimally at acidic pH - Chahinian_2006_Biochemistry_45_993
Author(s) : Chahinian H , Snabe T , Attias C , Fojan P , Petersen SB , Carriere F
Ref : Biochemistry , 45 :993 , 2006
Abstract : Gastric lipase is active under acidic conditions and shows optimum activity on insoluble triglycerides at pH 4. The present results show that gastric lipase also acts in solution on vinyl butyrate, with an optimum activity above pH 7, which suggests that gastric lipase is able to hydrolyze ester bonds via the classical mechanism of serine hydrolases. These results support previous structural studies in which the catalytic triad of gastric lipase was reported to show no specific features. The optimum activity of gastric lipase shifted toward lower pH values, however, when the vinyl butyrate concentration was greater than the solubility limit. Experiments performed with long-chain triglycerides showed that gastric lipase binds optimally to the oil-water interface at low pH values. To study the effects of the pH on the adsorption step independently from substrate hydrolysis, gastric lipase adsorption on solid hydrophobic surfaces was monitored by total internal reflection fluorescence (TIRF), as well as using a quartz crystal microbalance. Both techniques showed a pH-dependent reversible gastric lipase adsorption process, which was optimum at pH 5 (Kd = 6.5 nM). Lipase adsorption and desorption constants (ka = 147,860 M(-1) s(-1) and kd = 139 x 10(-4) s(-1) at pH 6) were estimated from TIRF experiments. These results indicate that the optimum activity of gastric lipase at acidic pH is only "apparent" and results from the fact that lipase adsorption at lipid-water interfaces is the pH-dependent limiting step in the overall process of insoluble substrate hydrolysis. This specific kinetic feature of interfacial enzymology should be taken into account when studying any soluble enzyme acting on an insoluble substrate.
ESTHER : Chahinian_2006_Biochemistry_45_993
PubMedSearch : Chahinian_2006_Biochemistry_45_993
PubMedID: 16411775

Title : Use of an inhibitor to identify members of the hormone-sensitive lipase family - Ben Ali_2006_Biochemistry_45_14183
Author(s) : Ben Ali Y , Chahinian H , Petry S , Muller G , Lebrun R , Verger R , Carriere F , Mandrich L , Rossi M , Manco G , Sarda L , Abousalham A
Ref : Biochemistry , 45 :14183 , 2006
Abstract : Hormone-sensitive lipase (HSL) contributes importantly to the mobilization of fatty acids from the triacylglycerols stored in adipocytes, which provide the main source of energy in mammals. On the basis of amino acid sequence alignments and three-dimensional structures, this enzyme was previously found to be a suitable template for defining a family of serine carboxylester hydrolases. In this study, the HSL family members are characterized rather on the basis of their inhibition by 5-methoxy-3-(4-phenoxyphenyl)-3H-[1,3,4]oxadiazol-2-one (compound 7600). This compound inhibits mammalian HSL as well as other HSL family members, such as EST2 from the thermophilic eubacterium Alicyclobacillus acidocaldarius and AFEST from the hyperthermophilic archaeon Archaeoglobus fulgidus. Various carboxylester hydrolases that are not members of the HSL family were found not to be inhibited by compound 7600 under the same experimental conditions. These include nonlipolytic hydrolases such as Torpedo californica acetylcholinesterase and pig liver esterase, as well as lipolytic hydrolases such as human pancreatic lipase, dog gastric lipase, Thermomyces lanuginosus lipase, and Bacillus subtilis LipA. When vinyl esters were used as substrates, the residual activity of HSL, AFEST, and EST2 decreased with an increase in compound 7600 concentration in the incubation mixture. The inhibitor concentration at which the enzyme activity decreased to 50% after incubation for 5 min was 70, 20, and 15 nM with HSL, AFEST, and EST2, respectively. Treating EST2 and AFEST with the inhibitor resulted in an increase in the molecular mass, as established by performing matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis. This increase in the molecular mass, which corresponds approximately to the molecular mass of the inhibitor, indicates that a covalent enzyme-inhibitor complex has been formed. Surface-enhanced laser desorption ionization time-of-flight mass spectrometry analysis of a trypsin digest of AFEST treated with the inhibitor or not treated showed the occurrence of an increase in the molecular masses of the "GESAGG"-containing peptide, which is compatible with the formation of a covalent complex with the inhibitor.
ESTHER : Ben Ali_2006_Biochemistry_45_14183
PubMedSearch : Ben Ali_2006_Biochemistry_45_14183
PubMedID: 17115713
Gene_locus related to this paper: human-LIPE

Title : Substrate specificity and kinetic properties of enzymes belonging to the hormone-sensitive lipase family: comparison with non-lipolytic and lipolytic carboxylesterases - Chahinian_2005_Biochim.Biophys.Acta_1738_29
Author(s) : Chahinian H , Ben Ali Y , Abousalham A , Petry S , Mandrich L , Manco G , Canaan S , Sarda L
Ref : Biochimica & Biophysica Acta , 1738 :29 , 2005
Abstract : We have studied the kinetics of hydrolysis of triacylglycerols, vinyl esters and p-nitrophenyl butyrate by four carboxylesterases of the HSL family, namely recombinant human hormone-sensitive lipase (HSL), EST2 from Alicyclobacillus acidocaldarius, AFEST from Archeoglobus fulgidus, and protein RV1399C from Mycobacterium tuberculosis. The kinetic properties of enzymes of the HSL family have been compared to those of a series of lipolytic and non-lipolytic carboxylesterases including human pancreatic lipase, guinea pig pancreatic lipase related protein 2, lipases from Mucor miehei and Thermomyces lanuginosus, cutinase from Fusarium solani, LipA from Bacillus subtilis, porcine liver esterase and Esterase A from Aspergilus niger. Results indicate that human HSL, together with other lipolytic carboxylesterases, are active on short chain esters and hydrolyze water insoluble trioctanoin, vinyl laurate and olive oil, whereas the action of EST2, AFEST, protein RV1399C and non-lipolytic carboxylesterases is restricted to solutions of short chain substrates. Lipolytic and non-lipolytic carboxylesterases can be differentiated by their respective value of K(0.5) (apparent K(m)) for the hydrolysis of short chain esters. Among lipolytic enzymes, those possessing a lid domain display higher activity on tributyrin, trioctanoin and olive oil suggesting, then, that the lid structure contributes to enzyme binding to triacylglycerols. Progress reaction curves of the hydrolysis of p-nitrophenyl butyrate by lipolytic carboxylesterases with lid domain show a latency phase which is not observed with human HSL, non-lipolytic carboxylesterases, and lipolytic enzymes devoid of a lid structure as cutinase.
ESTHER : Chahinian_2005_Biochim.Biophys.Acta_1738_29
PubMedSearch : Chahinian_2005_Biochim.Biophys.Acta_1738_29
PubMedID: 16325466

Title : Sensitive assay for hormone-sensitive lipase using NBD-labeled monoacylglycerol to detect low activities in rat adipocytes - Petry_2005_J.Lipid.Res_46_603
Author(s) : Petry S , Ben Ali Y , Chahinian H , Jordan H , Kleine H , Muller G , Carriere F , Abousalham A
Ref : J Lipid Res , 46 :603 , 2005
Abstract : The recent finding that p-nitrobenzofurazan (NBD)-FA is incorporated into and released from the acylglycerols of isolated rat adipocytes in an insulin-sensitive manner [G. Muller, H. Jordan, C. Jung, H. Kleine, and S. Petry. 2003. Biochimie. 85: 1245-1246] suggests that NBD-FA-labeled acylglycerols are cleaved by rat adipocyte hormone-sensitive lipase (HSL) in vivo. In the present study, we developed a continuous, sensitive in vitro lipase assay using a monoacylglycerol (MAG) containing NBD (NBD-MAG). NBD-MAG was found to provide an efficient substrate for rat adipocyte and human recombinant HSL. Ultrasonic treatment applied in the presence of phospholipids leads to the incorporation of NBD-MAG into the phospholipid liposomes and to a concomitant change of its spectrophotometric properties. The enzymatic release of NBD-FA and its dissociation from the carrier liposomes is accompanied by the recovery of the original spectrophotometric characteristics. The rate of lipolysis was monitored by measuring the increase in optical density at 481 nm, which was found to be linear with time and linearly proportional to the amount of lipase added. To assess the specific activity of recombinant HSL, we determined the molar extinction coefficient of NBD-FA under the assay conditions. This convenient assay procedure based on NBD-MAG should facilitate the search for small molecule HSL inhibitors.
ESTHER : Petry_2005_J.Lipid.Res_46_603
PubMedSearch : Petry_2005_J.Lipid.Res_46_603
PubMedID: 15627655
Gene_locus related to this paper: human-LIPE

Title : A. niger protein EstA, perhaps a new electrotactin, defines a new class of fungal esterases within the alpha\/beta hydrolase fold superfamily - Bourne_2005_Chem.Biol.Interact_157-158_395
Author(s) : Bourne Y , Hasper AA , Chahinian H , Renault L , Juin M , De Graaff LH , Marchot P
Ref : Chemico-Biological Interactions , 157-158 :395 , 2005
Abstract : Protein EstA from Aspergillus niger was characterized through a multifaced approach involving molecular biology, bioinformatics, biophysical, biochemical and enzymatical analyses. EstA was identified as the lead member, within the superfamily of proteins with an alpha/beta-hydrolase fold, of a new class of fungal esterases that also contains predicted homologs from other fungus species of known broad host-range pathogenicity.
ESTHER : Bourne_2005_Chem.Biol.Interact_157-158_395
PubMedSearch : Bourne_2005_Chem.Biol.Interact_157-158_395
PubMedID: 16429533
Gene_locus related to this paper: aspni-EstA

Title : Expression and characterization of the protein Rv1399c from Mycobacterium tuberculosis. A novel carboxyl esterase structurally related to the HSL family - Canaan_2004_Eur.J.Biochem_271_3953
Author(s) : Canaan S , Maurin D , Chahinian H , Pouilly B , Durousseau C , Frassinetti F , Scappuccini-Calvo L , Cambillau C , Bourne Y
Ref : European Journal of Biochemistry , 271 :3953 , 2004
Abstract : The Mycobacterium tuberculosis genome contains an unusually high number of proteins involved in the metabolism of lipids belonging to the Lip family, including various nonlipolytic and lipolytic hydrolases. Driven by a structural genomic approach, we have biochemically characterized the Rv1399c gene product, LipH, previously annotated as a putative lipase. Rv1399c was overexpressed in E. coli as inclusion bodies and refolded. Rv1399c efficiently hydrolyzes soluble triacylglycerols and vinyl esters. It is inactive against emulsified substrate and its catalytic activity is strongly inhibited by the diethyl paranitrophenyl phosphate (E600). These kinetic behaviors unambiguously classify Rv1399c as a nonlipolytic rather than a lipolytic hydrolase. Sequence alignment reveals that this enzyme belongs to the alpha/beta hydrolase fold family and shares 30-40% amino acid sequence identity with members of the hormone-sensitive lipase subfamily. A model of Rv1399c derived from homologous three-dimensional structures reveals a canonical catalytic triad (Ser162, His290 and Asp260) located at the bottom of a solvent accessible pocket lined by neutral or charged residues. Based on this model, kinetic data of the Arg213Ala mutant partially explain the role of the guanidinium moiety, located close to His290, to confer an unusual low pH shift of the catalytic histidine in the wild type enzyme. Overall, these data identify Rv1399c as a new nonlipolytic hydrolase from M. tuberculosis and we thus propose to reannotate its gene product as NLH-H.
ESTHER : Canaan_2004_Eur.J.Biochem_271_3953
PubMedSearch : Canaan_2004_Eur.J.Biochem_271_3953
PubMedID: 15373841
Gene_locus related to this paper: myctu-Rv1399c

Title : Might the kinetic behavior of hormone-sensitive lipase reflect the absence of the lid domain? - Ben Ali_2004_Biochemistry_43_9298
Author(s) : Ben Ali Y , Chahinian H , Petry S , Muller G , Carriere F , Verger R , Abousalham A
Ref : Biochemistry , 43 :9298 , 2004
Abstract : Hormone-sensitive lipase (HSL) is thought to contribute importantly to the mobilization of fatty acids from the triacylglycerols (TAGs) stored in adipocytes, providing the main source of energy in mammals. To investigate the HSL substrate specificity more closely, we systematically assessed the lipolytic activity of recombinant human HSL on solutions and emulsions of various vinyl esters and TAG substrates, using the pH-stat assay technique. Recombinant human HSL activity on solutions of partly soluble vinyl esters or TAG was found to range from 35 to 90% of the maximum activity measured with the same substrates in the emulsified state. The possible existence of a lipid-water interface due to the formation of small aggregates of vinyl esters or TAG in solution may account for the HSL activity observed below the solubility limit of the substrate. Recombinant human HSL also hydrolyzes insoluble medium- and long-chain acylglycerols such as trioctanoylglycerol, dioleoylglycerol, and olive oil, and can therefore be classified as a true lipase. Preincubation of the recombinant HSL with a serine esterase inhibitor such as diethyl p-nitrophenyl phosphate in 1:100 molar excess leads to complete HSL inhibition within 15 min. This result indicates that the catalytic serine of HSL is highly reactive and that it is readily accessible. Similar behavior was also observed with lipases with no lid domain covering their active site, or with a deletion in the lid domain. The 3-D structure of HSL, which still remains to be determined, may therefore lack the lid domain known to exist in various other lipases.
ESTHER : Ben Ali_2004_Biochemistry_43_9298
PubMedSearch : Ben Ali_2004_Biochemistry_43_9298
PubMedID: 15260473
Gene_locus related to this paper: human-LIPE

Title : Aspergillus niger protein EstA defines a new class of fungal esterases within the alpha\/beta hydrolase fold superfamily of proteins - Bourne_2004_Structure_12_677
Author(s) : Bourne Y , Hasper AA , Chahinian H , Juin M , De Graaff LH , Marchot P
Ref : Structure , 12 :677 , 2004
Abstract : From the fungus Aspergillus niger, we identified a new gene encoding protein EstA, a member of the alpha/beta-hydrolase fold superfamily but of unknown substrate specificity. EstA was overexpressed and its crystal structure was solved by molecular replacement using a lipase-acetylcholinesterase chimera template. The 2.1 A resolution structure of EstA reveals a canonical Ser/Glu/His catalytic triad located in a small pocket at the bottom of a large solvent-accessible, bowl-shaped cavity. Potential substrates selected by manual docking procedures were assayed for EstA activity. Consistent with the pocket geometry, preference for hydrolysis of short acyl/propyl chain substrates was found. Identification of close homologs from the genome of other fungi, of which some are broad host-range pathogens, defines EstA as the first member of a novel class of fungal esterases within the superfamily. Hence the structure of EstA constitutes a lead template in the design of new antifungal agents directed toward its pathogenic homologs.
ESTHER : Bourne_2004_Structure_12_677
PubMedSearch : Bourne_2004_Structure_12_677
PubMedID: 15062090
Gene_locus related to this paper: aspni-EstA

Title : The beta 5' loop of the pancreatic lipase C2-like domain plays a critical role in the lipase-lipid interactions - Chahinian_2002_Biochemistry_41_13725
Author(s) : Chahinian H , Bezzine S , Ferrato F , Ivanova MG , Perez B , Lowe ME , Carriere F
Ref : Biochemistry , 41 :13725 , 2002
Abstract : The structural similarities between the C-terminal domain of human pancreatic lipase (C-HPL) and C2 domains suggested a similar function, the interaction with lipids. The catalytic N-terminal domain (N-HPL) and C-HPL were produced as individual proteins, and their partitioning between the water phase and the triglyceride-water interface was assessed using trioctanoin emulsions (TC8). N-HPL did not bind efficiently to TC8 and was inactive. C-HPL did bind to TC8 and to a phospholipid monolayer with a critical surface pressure of penetration similar to that of HPL (15 mN m(-1)). These experiments, performed in the absence of colipase and bile salts, support an absolute requirement of C-HPL for interfacial binding of HPL. To refine our analysis, we determined the contribution to lipid interactions of a hydrophobic loop (beta 5') in C-HPL by investigating a HPL mutant in which beta 5' loop hydrophobicity was increased by introducing the homologous lipoprotein lipase (LPL) beta 5' loop. This mutant (HPL-beta 5'LPL) penetrated into phospholipid monolayers at higher surface pressures than HPL, and its level of binding to TC8 was higher than that of HPL in the presence of serum albumin (BSA), an inhibitory protein that competes with HPL for interfacial adsorption. The beta 5' loop of LPL is therefore tailored for an optimal interaction with the surface of triglyceride-rich lipoproteins (VLDL and chylomicrons) containing phospholipids and apoproteins. These observations support a major contribution of the beta 5' loop in the interaction of LPL and HPL with their respective substrates.
ESTHER : Chahinian_2002_Biochemistry_41_13725
PubMedSearch : Chahinian_2002_Biochemistry_41_13725
PubMedID: 12427035

Title : Distinction between esterases and lipases: a kinetic study with vinyl esters and TAG - Chahinian_2002_Lipids_37_653
Author(s) : Chahinian H , Nini L , Boitard E , Dubes JP , Comeau LC , Sarda L
Ref : Lipids , 37 :653 , 2002
Abstract : The better to characterize enzymes hydrolyzing carboxyl ester bonds (carboxyl ester hydrolases), we have compared the kinetic behavior of various lipases and esterases against solutions and emulsions of vinyl esters and TAG. Short-chain vinyl esters are hydrolyzed at comparable rates by esterases and lipases and have higher limits of solubility in water than corresponding TAG. Therefore, they are suited to study the influence of the physical state of the substrate on carboxyl ester hydrolase activity within a large concentration range. Enzymes used in this study are TAG lipases from microorganisms, lipases from human and guinea pig pancreas, pig liver esterase, and acetylcholinesterase. This study also includes cutinase, a fungal enzyme that displays functional properties between esterases and lipases. Esterases display maximal activity against solutions of short-chain vinyl esters (vinyl acetate, vinyl propionate, and vinyl butyrate) and TAG (triacetin, tripropionin, and tributyrin). Half-maximal activity is reached at ester concentrations far below the solubility limit. The transition from solution to emulsion at substrate concentrations exceeding the solubility limit has no effect on esterase activity. Lipases are active on solutions of short-chain vinyl esters and TAG but, in contrast to esterases, they all display maximal activity against emulsified substrates and half-maximal activity is reached at substrate concentrations near the solubility limit of the esters. The kinetics of hydrolysis of soluble substrates by lipases are either hyperbolic or deviate from the Michaelis-Menten model and show no or weak interfacial activation. The presence of molecular aggregates in solutions of short-chain substrates, as evidenced by a spectral dye method, likely accounts for the activity of lipases against soluble esters. Unlike esterases, lipases hydrolyze emulsions of water-insoluble medium- and long-chain vinyl esters and TAG such as vinyl laurate, trioctanoin, and olive oil. In conclusion, comparisons of the kinetic behavior of carboxyl ester hydrolases against solutions and emulsions of vinyl esters and TAG allows the distinction between lipases and esterases. In this respect, it clearly appears that guinea pig pancreatic lipase and cutinase are unambiguously classified as lipases.
ESTHER : Chahinian_2002_Lipids_37_653
PubMedSearch : Chahinian_2002_Lipids_37_653
PubMedID: 12216836

Title : Lipase-catalysed hydrolysis of short-chain substrates in solution and in emulsion: a kinetic study - Nini_2001_Biochim.Biophys.Acta_1534_34
Author(s) : Nini L , Sarda L , Comeau LC , Boitard E , Dubes JP , Chahinian H
Ref : Biochimica & Biophysica Acta , 1534 :34 , 2001
Abstract : We have studied the enzymatic hydrolysis of solutions and emulsions of vinyl propionate, vinyl butyrate and tripropionin by lipases of various origin and specificity. Kinetic studies of the hydrolysis of short-chain substrates by microbial triacylglycerol lipases from Rhizopus oryzae, Mucor miehei, Candida rugosa, Candida antarctica A and by (phospho)lipase from guinea-pig pancreas show that these lipolytic enzymes follow the Michaelis-Menten model. Surprisingly, the activity against solutions of tripropionin and vinyl esters ranges from 70% to 90% of that determined against emulsions. In contrast, a non-hyperbolic (sigmoidal) dependence of enzyme activity on ester concentration is found with human pancreatic lipase, triacylglycerol lipase from Humicola lanuginosa (Thermomyces lanuginosa) and partial acylglycerol lipase from Penicillium camembertii and the same substrates. In all cases, no abrupt jump in activity (interfacial activation) is observed at substrate concentration corresponding to the solubility limit of the esters. Maximal lipolytic activity is always obtained in the presence of emulsified ester. Despite progress in the understanding of structure-function of lipases, interpretation of the mode of action of lipases active against solutions of short-chain substrates remains difficult. Actually, it is not known whether these enzymes, which possess a lid structure, are in open or/and closed conformation in the bulk phase and whether the opening of the lid that gives access to the catalytic triad is triggered by interaction of the enzyme molecule with monomeric substrates or/and multimolecular aggregates (micelles) both present in the bulk phase. From the comparison of the behaviour of lipases used in this study which, in some cases, follow the Michaelis-Menten model and, in others, deviate from classical kinetics, it appears that the activity of classical lipases against soluble short-chain vinyl esters and tripropionin depends not only on specific interaction with single substrate molecules at the catalytic site of the enzyme but also on physico-chemical parameters related to the state of association of the substrate dispersed in the aqueous phase. It is assumed that the interaction of lipase with soluble multimolecular aggregates of tripropionin or short-chain vinyl esters or the formation of enzyme-substrate mixed micelles with ester bound to lipase, might represent a crucial step that triggers the structural transition to the open enzyme conformation by displacement of the lid.
ESTHER : Nini_2001_Biochim.Biophys.Acta_1534_34
PubMedSearch : Nini_2001_Biochim.Biophys.Acta_1534_34
PubMedID: 11750885

Title : Production of extracellular lipases by Penicillium cyclopium purification and characterization of a partial acylglycerol lipase - Chahinian_2000_Biosci.Biotechnol.Biochem_64_215
Author(s) : Chahinian H , Vanot G , Ibrik A , Rugani N , Sarda L , Comeau LC
Ref : Biosci Biotechnol Biochem , 64 :215 , 2000
Abstract : Penicillium cyclopium, grown in stationary culture, produces a type I lipase specific for triacylglycerols while, in shaken culture, it produces a type II lipase only active on partial acylglycerols. Lipase II has been purified by ammonium sulfate precipitation and chromatographies on Sephadex G-75 and DEAE-Sephadex. The enzyme exists in several glycosylated forms of 40-43 kDa, which can be converted to a single protein of 37 kDa by enzymatic deglycosylation. Activity of lipase II is maximal at pH 7.0 and 40 degrees C. The enzyme is stable from pH 4.5 to 7.0. Activity is rapidly lost at temperatures above 50 degrees C. The enzyme specifically hydrolyzes monoacylglycerols and diacylglycerols, especially of medium chain fatty acids. The sequence of the 20 first amino acid residues is similar to the N-terminal region of P. camembertii lipase and partially similar to lipases from Humicola lanuginosa and Aspergillus oryzae, but is different from Penicillium cyclopium lipase I. However, it can be observed that residues of valine and serine at positions 2 and 5 in Penicillium cyclopium lipase II are conserved in Penicillium expansum lipase, of which 16 out of the 20 first amino acid residues are similar to Penicillium cyclopium lipase I.
ESTHER : Chahinian_2000_Biosci.Biotechnol.Biochem_64_215
PubMedSearch : Chahinian_2000_Biosci.Biotechnol.Biochem_64_215
PubMedID: 10737172

Title : Kinetic properties of Penicillium cyclopium lipases studied with vinyl esters - Chahinian_2000_Lipids_35_919
Author(s) : Chahinian H , Nini L , Boitard E , Dubes JP , Sarda L , Comeau LC
Ref : Lipids , 35 :919 , 2000
Abstract : Penicillium cyclopium produces two lipases with different substrate specificities. Lipase I is predominantly active on triacylglycerols whereas lipase II hydrolyzes mono- and diacylglycerols but not triacylglycerols. In this study, we compared the kinetic properties of P. cyclopium lipases and human pancreatic lipase, a classical triacylglycerol lipase, by using vinyl esters as substrates. Results indicate that P. cyclopium lipases I and II and human pancreatic lipase hydrolyze solutions of vinyl propionate or vinyl butyrate at high relative rates compared with emulsions of the same esters, although, in all cases, maximal activity is reached in the presence of emulsified particles, at substrate concentrations above the solubility limit. It appears that partially water-soluble short-chain vinyl esters are suitable substrates for comparing the activity of lipolytic enzymes of different origin and specificity toward esters in solution and in emulsion.
ESTHER : Chahinian_2000_Lipids_35_919
PubMedSearch : Chahinian_2000_Lipids_35_919
PubMedID: 10984115

Title : The C-terminal domain of pancreatic lipase: functional and structural analogies with c2 domains - Chahinian_2000_Curr.Protein.Pept.Sci_1_91
Author(s) : Chahinian H , Sias B , Carriere F
Ref : Curr Protein Pept Sci , 1 :91 , 2000
Abstract : The 3D structure of pancreatic lipase (PL) consists of two functional domains. The N-terminal domain belongs to the alpha/beta hydrolase fold and contains the active site, which involves a catalytic triad analogous to that present in serine proteases. The beta-sandwich C-terminal domain of PL plays an important part in the binding process between the lipase and colipase, the specific PL cofactor. Recent structure-function studies have suggested that the PL C-terminal domain may have an extra role apart from that of binding colipase. This domain contains an exposed hydrophobic loop (beta5') which was found to be located on the same side as the hydrophobic loops surrounding the active site, and it may be involved in the lipid binding process. Indirect evidence for this new function of the PL C-terminal domain has been provided by studies with monoclonal antibodies directed against the beta5' loop. The catalytic activity of the PL-antibody complexes on water insoluble substrates decreased drastically, whereas their esterase activity on a soluble substrate remained unchanged. During the last few years, a number of protein structures (15-lipoxygenase, alpha-toxin from Clostridium perfringens) have been determined that contain domains with close structural homologies with the beta-sandwich C-terminal domain of PL. Generally speaking, these domains show structural homologies with the C2 domains occurring in a wide range of proteins involved in signal transduction (e.g. phosphoinositide-specific phospholipase C, protein kinase C, cytosolic phospholipase A2), membrane traffic (e.g. synaptotagmin I, rabphilin) and membrane disruption (e.g. perforin). Here it is proposed to review the structure and function of the C2 domains, based on the recent 3D structures and improved sequence alignments.
ESTHER : Chahinian_2000_Curr.Protein.Pept.Sci_1_91
PubMedSearch : Chahinian_2000_Curr.Protein.Pept.Sci_1_91
PubMedID: 12369922

Title : Biochemical and structural characterization of triacylglycerol lipase from Penicillium cyclopium - Ibrik_1998_Lipids_33_377
Author(s) : Ibrik A , Chahinian H , Rugani N , Sarda L , Comeau LC
Ref : Lipids , 33 :377 , 1998
Abstract : An extracellular lipase, active on water-insoluble triacylglycerols, has been isolated from Penicillium cyclopium. The purified enzyme has a molecular mass of 29 kDa by gel filtration and SDS-polyacrylamide gel electrophoresis. It hydrolyzes emulsions of tributyrin, trioctanoin, and olive oil at the same rate as pancreatic lipase and shows very low activity against partial acylglycerols (monooctanoin and dioctanoin) and methyl esters. It is stable at 35 degrees C for 60 min and has maximal activity in a pH range of 8-10. Hydrolysis of triacylglycerols by P. cyclopium lipase is inhibited by detergents such as Triton X-100. Comparison of the sequence of the 20 first amino acid residues of P. cyclopium triacylglycerol lipase with other Penicillium lipases indicates a high homology with previously characterized lipases produced by P. expansum and P. solitum which are enzymes of comparable size and substrate specificity. Conversely, homology between P. cyclopium lipase and P. simplicissimum lipase, a nonspecific lipolytic enzyme, is low. Penicillium cyclopium triacylglycerol lipase shows no homology with P. camembertii lipase which is specific to monoacylglycerol and diacylglycerol.
ESTHER : Ibrik_1998_Lipids_33_377
PubMedSearch : Ibrik_1998_Lipids_33_377
PubMedID: 9590625