Adkins S

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Full name : Adkins Steve

First name : Steve

Mail : Pharmacology Department. Medical Sci. Building 1, University of Michigan Medical School, Ann Arbor, MI 48109-0626

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Country : USA

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Phone : (1) 313 7473137

Fax : (l) 313 763 4450

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References (10)

Title : Reconsideration of the catalytic center and mechanism of mammalian paraoxonase\/arylesterase - Sorenson_1995_Proc.Natl.Acad.Sci.U.S.A_92_7187
Author(s) : Sorenson RC , Primo-Parmo SL , Kuo CL , Adkins S , Lockridge O , La Du BN
Ref : Proc Natl Acad Sci U S A , 92 :7187 , 1995
Abstract : For three decades, mammalian paraoxonase (A-esterase, aromatic esterase, arylesterase; PON, EC 3.1.8.1) has been thought to be a cysteine esterase demonstrating structural and mechanistic homologies with the serine esterases (cholinesterases and carboxyesterases). Human, mouse, and rabbit PONs each contain only three cysteine residues, and their positions within PON have been conserved. In purified human PON, residues Cys-41 and Cys-352 form an intramolecular disulfide bond and neither could function as an active-center cysteine. Highly purified, enzymatically active PON contains a single titratable sulfhydryl group. Thus, Cys-283 is the only probable candidate for an active-center cysteine. Through site-directed mutagenesis of the human cDNA, Cys-283 was replaced with either serine (C283S) or alanine (C283A). The expressed C283 (wild-type) enzyme was inactivated by para-hydroxymercuribenzoate, but the C283S and C283A mutant enzymes were not inactivated. C283A and C283S mutant enzymes retained both paraoxonase and arylesterase activities, and the Km values for paraoxon and phenyl acetate were similar to those of the wild type. Clearly, residue Cys-283 is free in active PON, but a free sulfhydryl group is not required for either paraoxonase or arylesterase activities. Consequently, it is necessary to examine other models for the active-site structure and catalytic mechanism of PON.
ESTHER : Sorenson_1995_Proc.Natl.Acad.Sci.U.S.A_92_7187
PubMedSearch : Sorenson_1995_Proc.Natl.Acad.Sci.U.S.A_92_7187
PubMedID: 7638166

Title : Recombinant human butyrylcholinesterase G390V, the fluoride-2 variant, expressed in Chinese hamster ovary cells, is a low affinity variant - Masson_1993_J.Biol.Chem_268_14329
Author(s) : Masson P , Adkins S , Gouet P , Lockridge O
Ref : Journal of Biological Chemistry , 268 :14329 , 1993
Abstract : Kinetics of recombinant fluoride-2 variant of human butyrylcholinesterase (Gly390 Val) secreted by Chinese hamster ovary cells were compared to recombinant usual and to usual butyrylcholinesterase purified from human plasma. The usual and fluoride-2 variant were indistinguishable with regard to hydrolysis of benzoylcholine (Km = 5 microM), neutral esters, and at high concentrations of acetylthiocholine, propionylthiocholine, and butyrylthiocholine. However, at low substrate concentrations Km values for acetylthiocholine and succinyldithiocholine were 2-6-fold higher for the fluoride-2 variant. pH rate profiles revealed small differences in pKa that could be attributed to changes in the active site histidine environment. On the other hand, Arrhenius plot analysis of o-nitrophenylbutyrate hydrolysis at pH 7.5 showed no difference in activation energy between fluoride-2 and usual butyrylcholinesterases. Both exhibited an anomalous temperature dependence with a wavelike change in activation energy around 18 degrees C. Affinity of the fluoride-2 variant for sodium fluoride, tacrine, dibucaine, amodiaquin, and succinyldicholine was lower than for usual enzyme. Apparent Ki for succinyldicholine was 125 microM for the fluoride-2 variant and 20 microM for the usual enzyme. Organophosphate inhibition showed equivalent reactivity, indicating that the point mutation altered only the binding properties of the variant. Thus, Km and Ki changes explain the succinyldicholine sensitivity of people carrying the fluoride-2 variant.
ESTHER : Masson_1993_J.Biol.Chem_268_14329
PubMedSearch : Masson_1993_J.Biol.Chem_268_14329
PubMedID: 8314794

Title : Studies on human serum paraoxonase\/arylesterase - La Du_1993_Chem.Biol.Interact_87_25
Author(s) : La Du BN , Adkins S , Kuo CL , Lipsig D
Ref : Chemico-Biological Interactions , 87 :25 , 1993
Abstract : The complete amino acid sequence of human serum paraoxonase/arylesterase and the DNA sequence coding for that protein have recently been determined in two independent laboratories. There is now considerable evidence that the esterase exists in two genetically determined allozymic forms, and these A and B allozymes possess both paraoxonase and arylesterase activities. The B-type esterase has relatively higher paraoxonase activity and is stimulated to a greater degree by 1 M NaCl than the A allozyme. The structural basis for the distinctive isozymic properties is a single nucleotide base at position 572. Codon 191 is CAA (for glutamine) in the A-type esterase, and CGA (for arginine) in the B-type enzyme. There is a second polymorphic site which affects amino acid 54; this can be either methionine or leucine, but these alternatives have not been found to affect either the level or the quality of the allozymes. Purified A or B-type esterases are stimulated by the addition of phosphatidylcholine. The latter addition increases the maximum velocity rate, but does not alter the Km of the reaction with either paraoxon or phenylacetate. In serum, the esterase is tightly bound to the high density lipoproteins, particularly apo A-1, but the importance of this association as far as the stability and catalytic properties of the esterase is not clear, and still under study. No physiological role of the esterase has been established, but its ability to hydrolyze several potent organophosphates may be of some significance in protecting against organophosphate toxicity.
ESTHER : La Du_1993_Chem.Biol.Interact_87_25
PubMedSearch : La Du_1993_Chem.Biol.Interact_87_25
PubMedID: 8393742

Title : Expression and Refolding of Functional Human Butyrylcholinesterase from E. Coli -
Author(s) : Masson P , Adkins S
Ref : In Multidisciplinary approaches to cholinesterase functions - Proceedings of Fourth International Meeting on Cholinesterases , (Shafferman, A. and Velan, B., Eds) Plenum Press, New York :49 , 1992
PubMedID:

Title : Identification of two different point mutations associated with the fluoride-resistant phenotype for human butyrylcholinesterase - Nogueira_1992_Am.J.Hum.Genet_51_821
Author(s) : Nogueira CP , Bartels CF , McGuire MC , Adkins S , Lubrano T , Rubinstein HM , Lightstone H , van der Spek AF , Lockridge O , La Du BN
Ref : American Journal of Human Genetics , 51 :821 , 1992
Abstract : The fluoride variant of human butyrylcholinesterase owes its name to the observation that it is resistant to inhibition by 0.050 mM sodium fluoride in the in vitro assay. Individuals who are heterozygous for the fluoride and atypical alleles experience about 30 min of apnea, rather than the usual 3-5 min, after receiving succinyldicholine. Earlier we reported that the atypical variant has a nucleotide substitution which changes Asp 70 to Gly. In the present work we have identified two different point mutations associated with the fluoride-resistant phenotype. Fluoride-1 has a nucleotide substitution which changes Thr 243 to Met (ACG to ATG). Fluoride-2 has a substitution which changes Gly 390 to Val (GGT to GTT). These results were obtained by DNA sequence analysis of the butyrylcholinesterase gene after amplification by PCR. The subjects for these analyses were 4 patients and 21 family members.
ESTHER : Nogueira_1992_Am.J.Hum.Genet_51_821
PubMedSearch : Nogueira_1992_Am.J.Hum.Genet_51_821
PubMedID: 1415224

Title : Poster: Expression of the fluoride variant of human butyrylcholinesterase in chinese hamster ovary cells -
Author(s) : Adkins S , Vaughan TA , Bartels CF , La Du BN , Lockridge O
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 :196 , 1991
PubMedID:

Title : Poster: Nomenclature for human butyrylcholinesterase genetic variants identified by DNA sequencing -
Author(s) : Lockridge O , Bartels CF , Nogueira CP , Arpagaus M , Adkins S , La Du BN
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 :193 , 1991
PubMedID:

Title : Poster: Identification of two different mutations associated with human butyrylcholinesterase fluoride resistance in serum -
Author(s) : Bartels CF , Nogueira CP , McGuire MC , Adkins S , Lockridge O , La Du BN , Rubinstein HM , Lubrano T , van der Spek AF , Lightstone H
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 :190 , 1991
PubMedID:

Title : Location of disulfide bonds within the sequence of human serum cholinesterase - Lockridge_1987_J.Biol.Chem_262_12945
Author(s) : Lockridge O , Adkins S , La Du BN
Ref : Journal of Biological Chemistry , 262 :12945 , 1987
Abstract : Human serum cholinesterase was digested with pepsin under conditions which left disulfide bonds intact. Peptides were isolated by high pressure liquid chromatography, and those containing disulfide bonds were identified by a color assay. Peptides were characterized by amino acid sequencing and composition analysis. Human serum cholinesterase contains 8 half-cystines in each subunit of 574 amino acids. Six of these form three internal disulfide bridges: between Cys65-Cys92, Cys252-Cys263, and Cys400-Cys519. A disulfide bond with Cys65 rather than Cys66 was inferred by homology with Torpedo acetylcholinesterase. Cys571 forms a disulfide bridge with Cys571 of an identical subunit. This interchain disulfide bridge is four amino acids from the carboxyl terminus. A peptide containing the interchain disulfide is readily cleaved from cholinesterase by trypsin (Lockridge, O., and La Du, B. N. (1982) J. Biol. Chem. 257, 12012-12018), suggesting that the carboxyl terminus is near the surface of the globular tetrameric protein. The disulfide bridges in human cholinesterase have exactly the same location as in Torpedo californica acetylcholinesterase. There is one potential free sulfhydryl in human cholinesterase at Cys66, but this sulfhydryl could not be alkylated. Comparison of human cholinesterase, and Torpedo and Drosophila acetylcholinesterases to the serine proteases suggests that the cholinesterases constitute a separate family of serine esterases, distinct from the trypsin family and from subtilisin.
ESTHER : Lockridge_1987_J.Biol.Chem_262_12945
PubMedSearch : Lockridge_1987_J.Biol.Chem_262_12945
PubMedID: 3115973

Title : Brain cDNA clone for human cholinesterase - McTiernan_1987_Proc.Natl.Acad.Sci.U.S.A_84_6682
Author(s) : McTiernan C , Adkins S , Chatonnet A , Vaughan TA , Bartels CF , Kott M , Rosenberry TL , La Du BN , Lockridge O
Ref : Proceedings of the National Academy of Sciences of the United States of America , 84 :6682 , 1987
Abstract : A cDNA library from human basal ganglia was screened with oligonucleotide probes corresponding to portions of the amino acid sequence of human serum cholinesterase (EC 3.1.1.8). Five overlapping clones, representing 2.4 kilobases, were isolated. The sequenced cDNA contained 207 base pairs of coding sequence 5' to the amino terminus of the mature protein in which there were four ATG translation start sites in the same reading frame as the protein. Only the ATG coding for Met-(-28) lay within a favorable consensus sequence for functional initiators. There were 1722 base pairs of coding sequence corresponding to the protein found circulating in human serum. The amino acid sequence deduced from the cDNA exactly matched the 574 amino acid sequence of human serum cholinesterase, as previously determined by Edman degradation. Therefore, our clones represented cholinesterase (EC 3.1.1.8) rather than acetylcholinesterase (EC 3.1.1.7). It was concluded that the amino acid sequences of cholinesterase from two different tissues, human brain and human serum, were identical. Hybridization of genomic DNA blots suggested that a single gene, or very few genes, coded for cholinesterase.
ESTHER : McTiernan_1987_Proc.Natl.Acad.Sci.U.S.A_84_6682
PubMedSearch : McTiernan_1987_Proc.Natl.Acad.Sci.U.S.A_84_6682
PubMedID: 3477799
Gene_locus related to this paper: human-BCHE