Giovannini E


Full name : Giovannini Elvio

First name : Elvio

Mail : Universita degli Studi di Perugia Facolta di Medicina e Chirurgia, Dipartimento di Medicina Sperimentale, Sez. Biologia cellulare e Molecolare, Via del Giochetto 06126 Perugia

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Country : Italy

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References (18)

Title : Organophosphate-resistant forms of acetylcholinesterases in two scallops--the Antarctic Adamussium colbecki and the Mediterranean Pecten jacobaeus - Romani_2006_Comp.Biochem.Physiol.B.Biochem.Mol.Biol_145_188
Author(s) : Romani R , Corsi I , Bonacci S , Focardi S , De Medio GE , De Santis A , Incarnato F , Giovannini E , Rosi G
Ref : Comparative Biochemistry & Physiology B Biochem Mol Biol , 145 :188 , 2006
Abstract : We describe the acetylcholinesterase polymorphisms of two bivalve molluscs, Adamussium colbecki and Pecten jacobaeus. The research was aimed to point out differences in the expression of pesticide-resistant acetylcholinesterase forms in organisms living in different ecosystems such as the Ross Sea (Antarctica) and the Mediterranean Sea. In A. colbecki, distinct acetylcholinesterase molecular forms were purified and characterized from spontaneously soluble, low-salt-soluble and low-salt-Triton extracts from adductor muscle and gills. They consist of two non-amphiphilic acetylcholinesterases (G(2), G(4)) and an amphiphilic-phosphatidylinositol-membrane-anchored form (G(2)); a further amphiphilic-low-salt-soluble G(2) acetylcholinesterase was found only in adductor muscle. In the corresponding tissues of P. jacobaeus, we found a non-amphiphilic G(4) and an amphiphilic G(2) acetylcholinesterase; amphiphilic-low-salt-soluble acetylcholinesterases (G(2)) are completely lacking. Such results are related with differences in cell membrane lipid compositions. In both scallops, all non-amphiphilic AChEs are resistant to used pesticides. Differently, the adductor muscle amphiphilic forms are resistant to carbamate eserine and organophosphate diisopropylfluorophosphate, but sensitive to organophoshate azamethiphos. In the gills of P. jacobaeus, amphiphilic G(2) forms are sensitive to all three pesticides, while the corresponding forms of A. colbecki are sensitive to eserine and diisopropylfluorophosphate, but resistant to azamethiphos. Results indicate that organophosphate and/or carbamate resistant AChE forms are present in species living in far different and far away environments. The possibility that these AChE forms could have ensued from a common origin and have been spread globally by migration is discussed.
ESTHER : Romani_2006_Comp.Biochem.Physiol.B.Biochem.Mol.Biol_145_188
PubMedSearch : Romani_2006_Comp.Biochem.Physiol.B.Biochem.Mol.Biol_145_188
PubMedID: 16931084

Title : Effects of chlorpyrifos on the catalytic efficiency and expression level of acetylcholinesterases in the bivalve mollusk Scapharca inaequivalvis - Romani_2005_Environ.Toxicol.Chem_24_2879
Author(s) : Romani R , Isani G , De Santis A , Giovannini E , Rosi G
Ref : Environ Toxicol Chem , 24 :2879 , 2005
Abstract : Three acetylcholinesterase (AChE) forms were detected and recovered from foot or gill tissues of the benthonic bivalve mollusk Scapharca inaequivalvis. A study was performed to investigate changes in catalytic and hydrodynamic features of these enzymes, as well as in their expression levels, after a 4-d or a 15-d exposure to a sublethal concentration (0.1 microl/L) of the pesticide chlorpyrifos (CPF). Both considered organs hold, in either CPF-exposed or untreated animals, two nonamphiphilic AChE forms, G2 and G4, which copurified on a procainamide-containing affinity gel and were separated by density gradient centrifugation. A third AChE form, an amphiphilic membrane-anchored G2, was also purified on the same affinity matrix from both organs. All enzymatic forms are true AChEs and are poorly inhibited by CPE They show different increases in the maximum velocity (Vmax) and in the Michaelis constant (Km) values after CPF exposure. Consequently, catalytic efficiency of AChEs, as defined by the ratio Vmax:Km, rises in the gills and drops in the foot. This would produce an overexpression of AChE-specific mRNAs. The effect was longer lasting in the foot. The combined results indicate that overexpression of enzymes in the presence of organophosphate (OP) may be a consequence of OP resistance itself. Again, the resistance of the organism to CPF seem to depend mainly on the resulting increase in AChE content.
ESTHER : Romani_2005_Environ.Toxicol.Chem_24_2879
PubMedSearch : Romani_2005_Environ.Toxicol.Chem_24_2879
PubMedID: 16398125

Title : Increased acetylcholinesterase activities in specimens of Sparus auratus exposed to sublethal copper concentrations - Romani_2003_Chem.Biol.Interact_145_321
Author(s) : Romani R , Antognelli C , Baldracchini F , De Santis A , Isani G , Giovannini E , Rosi G
Ref : Chemico-Biological Interactions , 145 :321 , 2003
Abstract : The present study looks at possible changes in the activity of acetylcholinesterase (AChE) in tissues (brain and white muscle) of the Mediterranean bony fish Sparus auratus after a 20 days exposure to sublethal concentrations (0.1 or 0.5 ppm) of copper in the marine water and on control untreated animals. The trials also included measurements of Cu concentration in the tissues to evaluate possible metal accumulation. Moreover, sedimentation analysis as well as V(max) and K(m) determination were carried out in tissue extracts of Cu-exposed or control animals. V(max) and K(m) were also determined with or without addition of Cu(2+) in the assay. No Cu accumulation occurred in brain and muscle after Cu exposure. AChE showed in both tissues a molecular polymorphism with putative globular (G) and asymmetric (A) forms. Cu exposition led to an increased specific activity and improved catalytic efficiency of AChE in brain and muscle, seemingly regarding G forms. The increase in catalytic efficiency also resulted from the in vitro assay with tissue extracts and Cu(2+) addition. The higher AChE activity and catalytic efficiency in both tissues after Cu exposition and without metal accumulation, suggests an increase of free Cu aliquot into the cells, likely due to mechanisms of metal homeostasis.
ESTHER : Romani_2003_Chem.Biol.Interact_145_321
PubMedSearch : Romani_2003_Chem.Biol.Interact_145_321
PubMedID: 12732458

Title : Different expressions of organophosphate-resistant acetylcholinesterases in the bivalve mollusk Scapharca inaequivalvis living in three different habitats - Talesa_2002_Environ.Toxicol.Chem_21_102
Author(s) : Talesa V , Romani R , Antognelli C , Giovannini E , Rosi G
Ref : Environ Toxicol Chem , 21 :102 , 2002
Abstract : The benthic mollusk Scapharca inaequivalvis was collected in spring 1999 from three areas of the northern Adriatic Sea From the mollusk molecular forms of acetylcholinesterase AChE consisting of two prevailing spontaneously soluble SS forms present in the blood were obtained These forms are a globular tetramer SSG4 a dimer SSG2 of catalytic subunits and a minor amphiphilic globular dimer low-salt Triton LST G2 phosphatidylinositol tailed All SS and LST forms partially purified by affinity chromatography are AChEs with a marked substrate specificity for acetylthiocholine and poor hydrolysis with butyrylthiocholine They are poorly inhibited by carbamate eserine and show a different pattern of inhibition by organophosphate diisopropylfluorophosphate DFP with totally resistant SS forms from clams collected from the two stations nearest the Po River Acetylcholinesterase SS and LST forms are expressed at highest lowest and middle levels in clams collected from the northern station closer to the Po delta and from the two more southern ones respectively The possibility that the expression pattern of AChE forms is due to effects of single or mixed classes of chemical pollutants is discussed
ESTHER : Talesa_2002_Environ.Toxicol.Chem_21_102
PubMedSearch : Talesa_2002_Environ.Toxicol.Chem_21_102
PubMedID: 11804042

Title : Soluble and membrane-bound acetylcholinesterases in Mytilus galloprovincialis (Pelecypoda: Filibranchia) from the northern Adriatic sea - Talesa_2001_Chem.Biol.Interact_134_151
Author(s) : Talesa V , Romani R , Antognelli C , Giovannini E , Rosi G
Ref : Chemico-Biological Interactions , 134 :151 , 2001
Abstract : Three forms of acetylcholinesterase (AChE) were detected in samples of the bivalve mollusc Mytilus galloprovincialis collected in sites of the Adriatic sea. Apart from the origin of the mussels, two spontaneously soluble (SS) AChE occur in the hemolymph and represent about 80% of total activity, perhaps hydrolyzing metabolism-borne choline esters. These hydrophilic enzymes (forms A and B) copurified by affinity chromatography (procainamide-Sepharose gel) and were separated by sucrose gradient centrifugation. They are, respectively, a globular tetramer (11.0-12.0 S) and a dimer (6.0-7.0 S) of catalytic subunits. The third form, also purified from tissue extracts by the same affinity matrix, proved to be an amphiphilic globular dimer (7.0 S) with a phosphatidylinositol tail giving cell membrane insertion, detergent (Triton X-100, Brij 96) interaction and self-aggregation. Such an AChE is likely functional in cholinergic synapses. All three AChE forms show a good substrate specificity and are inactive on butyrylthiocholine. Studies with inhibitors showed low inhibition by eserine and paraoxon, especially on SS forms, high sensitivity to 1,5-bis(4-allyldimethylammoniumphenyl)-pentan-3-one dibromide (BW284c51) and no inhibition with propoxur and diisopropylfluorophosphate (DFP). The ChE forms in M. galloprovincialis are possibly encoded by different genes. Some kinetic features of these enzymes suggest a genetic polymorphism.
ESTHER : Talesa_2001_Chem.Biol.Interact_134_151
PubMedSearch : Talesa_2001_Chem.Biol.Interact_134_151
PubMedID: 11311211

Title : Molecular cloning and expression of a full-length cDNA encoding acetylcholinesterase in optic lobes of the squid Loligo opalescens: a new member of the cholinesterase family resistant to diisopropyl fluorophosphate - Talesa_1999_J.Neurochem_72_1250
Author(s) : Talesa V , Grauso M , Arpagaus M , Giovannini E , Romani R , Rosi G
Ref : Journal of Neurochemistry , 72 :1250 , 1999
Abstract : Acetylcholinesterase cDNA was cloned by screening a library from Loligo opalescens optic lobes; cDNA sequence analysis revealed an open reading frame coding for a protein of 610 amino acids that showed 20-41% amino acid identity with the acetylcholinesterases studied so far. The characteristic structure of cholinesterase (the choline binding site, the catalytic triad, and six cysteines that form three intrachain disulfide bonds) was conserved in the protein. The heterologous expression of acetylcholinesterase in COS cells gave a recovery of acetylcholinesterase activity 20-fold higher than in controls. The enzyme, partially purified by affinity chromatography, showed molecular and kinetic features indistinguishable from those of acetylcholinesterase expressed in vivo, which displays a high catalytic efficiency. Both enzymes are true acetylcholinesterase corresponding to phosphatidylinositol-anchored G2a dimers of class I, with a marked substrate specificity for acetylthiocholine. The deduced amino acid sequence may explain some particular kinetic characteristics of Loligo acetylcholinesterase, because the presence of a polar amino acid residue (S313) instead of a nonpolar one [F(288) in Torpedo] in the acyl pocket of the active site could justify the high substrate specificity of the enzyme, the absence of hydrolysis with butyrylthiocholine, and the poor inhibition by the organophosphate diisopropyl fluorophosphate.
ESTHER : Talesa_1999_J.Neurochem_72_1250
PubMedSearch : Talesa_1999_J.Neurochem_72_1250
PubMedID: 10037498
Gene_locus related to this paper: lolop-ACHE1

Title : Molecular Cloning and Characterization of a cDNA Encoding AChE from Optic Lobe of Loligo Opalescences -
Author(s) : Talesa V , Grauso M , Arpagaus M , Giovannini E , Rosi G
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :143 , 1998

Title : Acetylcholinesterase at high catalytic efficiency and substrate specificity in the optic lobe of Eledone moschata (Cephalopoda: Octopoda): biochemical characterization and histochemical localization - Talesa_1998_Neurochem.Int_33_131
Author(s) : Talesa V , Romani R , Calvitti M , Rosi G , Giovannini E
Ref : Neurochem Int , 33 :131 , 1998
Abstract : In the optic lobe of the cephalopod mollusc Eledone moschata, two acetylcholinesterase forms I and II were detected, both showing a marked active site specificity with differently sized substrates. Catalytic efficiency (kcat/Km) of the prevailing form II is similar to that of acetylcholinesterases from vertebrate nervous system. Enzyme forms I and II were co-purified from a high-salt-Triton X-100 soluble extract of optic lobe by consecutive affinity chromatographies on procainamide- and concanavalin A-Sepharose columns and then separately obtained by preparative density gradient centrifugation. According to gel-filtration chromatography, sedimentation analysis and SDS-PAGE, the major form II is an amphiphilic globular dimer (135-136 kDa, 6.3-7.4 S) of monomers (66 kDa) S-S linked between terminal segments. Phosphatidylinositol anchors give cell membrane insertion, self-aggregation and detergent (Triton X-100, Brij 97) interaction. Form I, characterized only in part owing to its small amount, showed molecular size (129 kDa) and sedimentation coefficient (7.5 S) similar to those of form II; it is likely to be attached to the cell membrane by electrostatic interactions. Both forms behaved similarly with various inhibitors and underwent excess-substrate inhibition. The results obtained suggest a common origin of both form I and II from a single gene. The former could be a degradation product of the prevailing one (II), which is likely to be functional in cholinergic synapses.
ESTHER : Talesa_1998_Neurochem.Int_33_131
PubMedSearch : Talesa_1998_Neurochem.Int_33_131
PubMedID: 9761457

Title : Synthesis and study of thiocarbonate derivatives of choline as potential inhibitors of acetylcholinesterase - Boyle_1997_J.Med.Chem_40_3009
Author(s) : Boyle NA , Talesa V , Giovannini E , Rosi G , Norton SJ
Ref : Journal of Medicinal Chemistry , 40 :3009 , 1997
Abstract : Fourteen alkyl and aryl thiocarbonate derivatives of choline were synthesized and studied as potential inhibitors of acetylcholinesterase (AChE). Twelve of the compounds inhibited AChEs derived from calf forebrain, human red blood cells, and octopus brain ranging from low to moderately high inhibition potency. The concentration of each inhibitory compound giving 50% inhibition of enzyme activity (IC50 values, which ranged from 1 x 10(-2) to 8 x 10(-7) M) was determined and is reported; inhibitor constants (Ki values) for the most inhibitory compounds, (1-pentylthiocarbonyl)choline chloride and (1-heptylthiocarbonyl)choline chloride, were calculated from kinetic data and are also reported. The inhibitors are competitive with substrate, and they are not hydrolyzed by the AChE activities. Certain of these new compounds may provide direction for the development of new drugs that have anticholinesterase activity and may be used for the treatment of Alzheimer's disease.
ESTHER : Boyle_1997_J.Med.Chem_40_3009
PubMedSearch : Boyle_1997_J.Med.Chem_40_3009
PubMedID: 9301662

Title : Expression of a single dimeric membrane-bound acetylcholinesterase in Parascaris equorum - Talesa_1997_Parasitology_115_653
Author(s) : Talesa V , Romani R , Grauso M , Rosi G , Giovannini E
Ref : Parasitology , 115 :653 , 1997
Abstract : A single form of cholinesterase was detected in the parasitic nematode Parascaris equorum and purified from a low-salt Triton X-100 extract of whole animals by affinity chromatography on an edrophonium-Sepharose matrix. Based on gel-filtration chromatography, sedimentation analysis and SDS-PAGE, such a cholinesterase is an amphiphilic globular (G2) dimer (125-129 kDa, 6.1 S). It includes some hydrophobic domain other than phosphatidylinositol, which gives autoaggregation, detergent interaction and also anchors the molecule to the cell membrane. The enzyme, probably functional in cholinergic neurotransmission, is an acetylcholinesterase showing a fairly low substrate specificity with thiocholine esters. Electrostatic interactions seem to play a major role in the catalytic activity. Studies with inhibitors gave complete inhibition with 1 mM eserine, low sensitivity for procainamide and for tetra(monoisopropyl)pyrophosphortetramide as well as higher inhibition with edrophonium chloride and 1,5-bis(4allyldimethylammoniumphenyl)-pentan-3-one dibromide. The enzyme also showed excess-substrate inhibition with acetylthiocholine. No cross-hybridization occurred between the gene(s) encoding acetylcholinesterase in P. equorum and ace-1 from the free-living nematode Caenorhabditis elegans. The expression of a single cholinesterase form in P. equorum, unusual in free-living nematodes, could be due to parasitic life adaptation with resulting reduction of locomotor activity.
ESTHER : Talesa_1997_Parasitology_115_653
PubMedSearch : Talesa_1997_Parasitology_115_653
PubMedID: 9488877

Title : Acetylcholinesterase in Dendrobaena veneta (Oligochaeta: Opisthopora) is present with forms sensitive and insensitive to phosphatidylinositol phospholipase C. Biochemical characterization and histochemical localization in the nervous system - Talesa_1996_Eur.J.Biochem_238_538
Author(s) : Talesa V , Romani R , Rosi G , Giovannini E
Ref : European Journal of Biochemistry , 238 :538 , 1996
Abstract : Three distinct acetylcholinesterases were detected in the annelid oligochaete Dendrobaena veneta. Two enzymes (alpha, beta), copurified from a Triton-X-100-soluble extract of whole animals by affinity (edrophonium-Sepharose) chromatography, were separately eluted from a Sephadex G-200 column. Gel-filtration chromatography, sedimentation analysis and SDS/PAGE showed the alpha and beta forms to be a globular dimer (110 kDa, 7.0 S) and a hydrophilic monomer (58 kDa, 5.0 S) respectively, both weakly linked to the cell membrane. The third form (gamma), also purified to homogeneity by slower filtration through an edrophonium-Sepharose matrix, proved to be an amphiphilic globular dimer (133 kDa, 7.0 S) with a phosphatidylinositol anchor giving cell membrane insertion, detergent (Triton X-100, Brij 96) interaction and self-aggregation. The alpha acetylcholinesterase showed a fairly low substrate specificity: the beta form hydrolyzed propionylthiocholine at the highest rate and was inactive on butyrylthiocholine; the gamma acetylcholinesterase, showing a marked active-site specificity with differently sized substrates, was likely functional in cholinergic synapses. Studies with inhibitors showed incomplete inhibition of all three acetylcholinesterase by 1 mM eserine and different sensitivity for edrophonium or procainamide. The alpha and beta forms, sensitive to 1,5-bis(4-allyldimethylammoniumphenyl)-pentan-3-one dibromide, were unaffected by tetra(monoisopropyl)-pyrophosphortetramide, while both these agents inhibited the gamma enzyme. All three forms showed excess-substrate inhibition by acetylthiocholine. Enzyme activity was histochemically localized in the nerve ring and its minor branches. Monomeric acetylcholinesterase (beta) is likely the only form present in the ganglionic glial framework.
ESTHER : Talesa_1996_Eur.J.Biochem_238_538
PubMedSearch : Talesa_1996_Eur.J.Biochem_238_538
PubMedID: 8681969

Title : Acetylcholinesterase in tentacles of Octopus vulgaris (Cephalopoda). Histochemical localization and characterization of a specific high salt-soluble and heparin-soluble fraction of globular forms - Talesa_1995_Neurochem.Int_27_201
Author(s) : Talesa V , Grauso M , Giovannini E , Rosi G , Toutant JP
Ref : Neurochem Int , 27 :201 , 1995
Abstract : Transverse sections of Octopus tentacles were stained for acetylcholinesterase (AChE) activity. An intense staining, that was suppressed by preincubation in 10(-5) M eserine, was detected in a number of neuronal cells, nerve fibres and neuromuscular junctions of intrinsic muscles of the arm. Octopus acetylcholinesterase was found as two molecular forms: an amphiphilic dimeric form (G2) sensitive to phosphatidylinositol phospholipase C and a hydrophilic tetrameric (G4) form. Sequential solubilization revealed that a significant portion of both G2 and G4 forms was recovered only in a high salt-soluble fraction (1 M NaCl, no detergent), Heparin (2 mg/ml) was able to solubilize G2 and G4 forms with the same efficiency than 1 M NaCl. The solubilizing effect of heparin was concentration-dependent and was reduced by protamine (2 mg/ml). This suggests that heparin operates through the dissociation of ionic interactions existing in situ between globular forms of AChE and cellular or extracellular polyanionic components. Interaction of AChE molecular forms with heparin has been reported so far in only a few instances and its physiological meaning is uncertain. G2 and G4 forms, interacting or not with heparin, all belong to a single pharmacological class of AChE. This suggests the existence of a single AChE gene. Amphiphilic and hydrophilic subunits thus likely result either from the processing of a single AChE transcript by alternative splicing (as in vertebrate AChE) or from a post-translation modification of a single catalytic peptide.
ESTHER : Talesa_1995_Neurochem.Int_27_201
PubMedSearch : Talesa_1995_Neurochem.Int_27_201
PubMedID: 7580876

Title : Acetylcholinesterase from Octopus vulgaris (Cephalopoda) -
Author(s) : Talesa V , Grauso M , Giovannini E , Rosi G , Toutant JP
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :127 , 1995

Title : Molecular Polymorphism of Acetylcholinesterase in Hirudo medicinalis -
Author(s) : Talesa V , Grauso M , Giovannini E , Rosi G , Toutant JP
Ref : In Enzyme of the Cholinesterase Family - Proceedings of Fifth International Meeting on Cholinesterases , (Quinn, D.M., Balasubramanian, A.S., Doctor, B.P., Taylor, P., Eds) Plenum Publishing Corp. :128 , 1995

Title : Solubilization, molecular forms, purification and substrate specificity of two acetylcholinesterases in the medicinal leech (Hirudo medicinalis) - Talesa_1995_Biochem.J_306_687
Author(s) : Talesa V , Grauso M , Giovannini E , Rosi G , Toutant JP
Ref : Biochemical Journal , 306 :687 , 1995
Abstract : Two acetylcholinesterases (AChE) differing in substrate and inhibitor specificities have been characterized in the medical leech (Hirudo medicinalis). A 'spontaneously-soluble' portion of AChE activity (SS-AChE) was recovered from haemolymph and from tissues dilacerated in low-salt buffer. A second portion of AChE activity was obtained after extraction of tissues in low-salt buffer alone or containing 1% Triton X-100 [detergent-soluble (DS-) AChE). Both enzymes were purified to homogeneity by affinity chromatography on edrophonium- and concanavalin A-Sepharose columns. Denaturing SDS/PAGE under reducing conditions gave one band at 30 kDa for purified SS-AChE and 66 kDa for DS-AChE. Sephadex G-200 chromatography indicated a molecular mass of 66 kDa for native SS-AChE and of 130 kDa for DS-AChE. SS-AChE showed a single peak sedimenting at 5.0 S in sucrose gradients with or without Triton X-100, suggesting that it was a hydrophylic monomer (G1). DS-AChE sedimented as a single 6.1-6.5 S peak in the presence of Triton X-100 and aggregated in the absence of detergent. A treatment with phosphatidylinositol-specific phospholipase C suppressed aggregation and gave a 7 S peak. DS-AChE was thus an amphiphilic glycolipid-anchored dimer. Substrate specificities were studied using p-nitrophenyl esters (acetate, propionate and butyrate) and corresponding thiocholine esters as substrates. SS-AChE displayed only limited variations in Km values with charged and uncharged substrates, suggesting a reduced influence of electrostatic interactions in the enzyme substrate affinity. By contrast, DS-AChE displayed higher Km values with uncharged than with charged substrates. SS-AChE was more sensitive to eserine and di-isopropyl fluorophosphate (IC50 5 x 10(-8) and 10(-8) M respectively) than DS-AChE (5 x 10(-7) and 5 x 10(-5) M.
ESTHER : Talesa_1995_Biochem.J_306_687
PubMedSearch : Talesa_1995_Biochem.J_306_687
PubMedID: 7702560

Title : Dimeric forms of cholinesterase in Sipunculus nudus - Talesa_1993_Eur.J.Biochem_215_267
Author(s) : Talesa V , Principato GB , Giovannini E , Di Giovanni MV , Rosi G
Ref : European Journal of Biochemistry , 215 :267 , 1993
Abstract : In developing a research on the cholinesterase (ChE) evolution in Invertebrata, this enzyme was studied in the unsegmented marine worm Sipunculus nudus. ChE activity was solubilized through three successive steps of extraction. These fractions are noted as low-salt (LSS), detergent (DS) and high-salt soluble (HSS) and represent 27%, 68% and 5% of total activity, respectively. LSS and DS ChE were purified to homogeneity by affinity chromatography on edrophonium-Sepharose gel. Purification factors of 1700 (LSS) and 1090 (DS) were obtained. The small amount of HSS ChE prevented a similar purification and an extensive characterization. Based on SDS/PAGE and density-gradient centrifugation, both LSS and DS enzymes show a M(r) value of about 130,000 and are likely G2 globular dimers of a 67,000 subunit. Moreover, LSS ChE seems to be an amphiphilic form including a hydrophobic domain, while DS ChE is probably linked to the cell membrane by a phosphatidylinositol anchor. Both LSS and DS enzymes hydrolyze at the highest rate propionylthiocholine. However, they also show a fairly high catalytic efficiency with other thiocholine esters as substrates, thus suggesting a wide and little-specialized conformation of the active site. Based on immunological cross-reactivity trials, LSS and DS ChE from S. nudus show a reduced structural affinity with a molluscan (Murex brandaris) enzyme. HSS ChE, an acetylcholinesterase, is also solubilized by heparin, like typical vertebrate HSS asymmetric enzymes. However, it lacks fast-sedimenting forms and an enzyme-anchoring collagenous structure.
ESTHER : Talesa_1993_Eur.J.Biochem_215_267
PubMedSearch : Talesa_1993_Eur.J.Biochem_215_267
PubMedID: 8344295

Title : Poster: Cholinesterases from invertebrates: A comparison of kinetic constants with different thiocholine esters as substrates -
Author(s) : Principato GB , Contenti S , Talesa V , Mangiabene C , Giovannini E , Rosi G , Pascolini R
Ref : In: Cholinesterases: Structure, Function, Mechanism, Genetics, and Cell Biology , (Massoulie J, Barnard EA, Chatonnet A, Bacou F, Doctor BP, Quinn DM) American Chemical Society, Washington, DC :273 , 1991

Title : [Purification and partial characterization of cholinesterase in Palaemonetes varians]. [Italian] -
Author(s) : Talesa V , Mangiabene C , Contenti S , Principato GB , Giovannini E , Rosi G
Ref : Bollettino Societa Italiana Biologia Sperimentale , 64 :227 , 1988
PubMedID: 3190885