摘要：

An enzyme hydrolyzing 4- to 8-carbon γ-lactones has been purified 12- to 15-fold from rat liver and from human plasma. In rat liver the enzyme is located in the microsomal fraction and may be solubilized by deoxycholate treatment and separated from microsomal B-esterase by ammonium sulfate fractionation. The effects of a series of inhibitors on γ-lactonase, B-esterase purified from rat liver microsomes, and plasma cholinesterase were compared. The lactonase was inhibited by 1 methylenediaminetetraacetate and by 0.1 m-chloromercuribenzoate but was unaffected by sodium benzoate, NaF, neostigmine, eserine, and diisopropylfluorophosphate. The last compound inactivates completely both the B-esterase and the cholinesterase, which were unaffected by ethylenediaminetetraacetate and were effectively inhibited by neostigmine. Together with substrate selectivity, these distinctions in inhibition establish the three enzymes as separate entities.

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