engleski

Variants of human serum esterases reacting with organophosphates, carbamates and pyridinium oximes

Our studies on biochemical properties of genetic variants of butyrylcholinesterase (EC 3.1.1.8) and of paraoxonase (EC 3.1.8.1) in human sera are summarised with respect to possible individual and population differences concerning their interaction with organophosphates (OPs), carbamates or pyridinium oximes. Serum butyrylcholinesterase occurs as the usual, the atypical and several other genetic variants. Butyrylcholinesterase variants differ in their susceptibilities to positively charged organophosphates and carbamates. The atypical variant has a lower affinity for all positively charged compounds and therefore is a less efficient scavenger for these compounds than the usual enzyme. This property of the atypical butyrylcholinesterase is also unfavourable due to its lower affinity for the positively charged oximes PAM-2 and HI-6, used in the therapy after intoxication by OPs. However, individuals with homozygous atypical cholinesterase are very rare. Paraoxonase, the most extensively studied phosphoric triester hydrolase, has two genetic variants, one with low and the other with high catalytic activity for paraoxon and some other OPs. If exposed to OPs, individuals with low paraoxonase activity might be at risk. A higher incidence of low paraoxonase activity has been observed in patients with glucose and lipid metabolism disorders or renal failure. However, to predict the genetic predisposition of an individual to adverse effects of OPs not only esterases reacting with OPs, but the over all detoxification capacity should be examined.

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nije evidentirano