Abstract
The hydrolysis of paraoxon (POX), phenylacetate (PA) and beta-naphthylacetate (BNA) was studied in human serum. Based upon correlations between enzyme activities, upon reversible inhibition by EDTA and upon progressive inhibition by iso-OMPA, tabun, eserine and bis-4 nitrophenylphosphate, the following conclusions were drawn about the number and specificity of enzymes involved in the hydrolysis. Two paraxonases hydrolyse paraoxon: one sensitive and the other insensitive to EDTA. The EDTA-sensitive paraoxonase also hydrolysed BNA. The EDTA-insensitive hydrolysis of BNA and PA was attributed to a serine esterase. The EDTA-sensitive hydrolysis of PA is probably due to more than one enzyme, which might be an arylesterase and a carboxylesterase.
MeSH terms
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Adolescent
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Adult
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Aged
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Aged, 80 and over
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Aryldialkylphosphatase
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Cholinesterase Inhibitors / pharmacology
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Cholinesterases / metabolism
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Edetic Acid / pharmacology
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Esterases / antagonists & inhibitors
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Esterases / blood*
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Esterases / classification
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Female
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Humans
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Hydrolysis
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Kinetics
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Male
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Middle Aged
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Naphthaleneacetic Acids / metabolism
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Nitrophenols / pharmacology
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Organophosphates / pharmacology
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Organophosphorus Compounds / blood
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Organophosphorus Compounds / metabolism*
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Paraoxon / metabolism
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Phenylacetates / metabolism
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Phosphoric Monoester Hydrolases / metabolism
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Physostigmine / pharmacology
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Sensitivity and Specificity
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Substrate Specificity
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Tetraisopropylpyrophosphamide / pharmacology
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Thiocholine / analogs & derivatives
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Thiocholine / metabolism
Substances
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Cholinesterase Inhibitors
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Naphthaleneacetic Acids
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Nitrophenols
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Organophosphates
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Organophosphorus Compounds
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Phenylacetates
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propionylthiocholine
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Tetraisopropylpyrophosphamide
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2-naphthylacetic acid
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Thiocholine
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bis(4-nitrophenyl)phosphate
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Edetic Acid
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Physostigmine
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Esterases
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Cholinesterases
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Phosphoric Monoester Hydrolases
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Aryldialkylphosphatase
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phenylacetic acid
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Paraoxon
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tabun