Some immunochemical properties of beef liver esterase

Genetics of esterases in Drosophila. IV. Slow-migrating S-esterase in Drosophila of the virilis group

A slow-migrating beta-esterase (S-esterase) is described which has been detected in Drosophila montana, Drosophila imeretensis, and some stocks of Drosophila virilis when mixtures of alpha- and beta-naphthyl acetate are used as substrates in histochemical reactions after electrophoresis. Sexual dimorphism for S-esterase has been demonstrated. This esterase is contained in male genitalia only, predominantly in the ejaculatory bulb (waxy plug). It appears 3-4 days after emergence of flies. In hybrids between S+ and So species, the activity of the slow esterase is either decreased or inhibited. An autonomous synthesis of the S- esterase in the ejaculatory bulb was established by transplantation of imaginal genital discs into larvae of different Drosophila stocks. Based on analysis of physiochemical and immunochemical properties, S-esterase is suggested to be an independent fraction of esterase, possibly dimeric, which does not cross-react with beta-esterase antiserum.

Characterization of an inducible amidase from Pseudomonas acidovorans AE1

The main molecular and catalytic properties of an acetanilide-hydrolyzing enzyme from Pseudomonas acidovorans AE 1, purified to a homogeneous state, were investigated. The molecular weight was 57 500 as determined by gel filtration and 55 300 as computed from the amino acid composition. By polyacrylamide gel electrophoresis in dodecylsulfate a polypeptide chain weight of 56 700 was obtained. Based on the reaction of the highly purufied enzyme with diethyl-4-nitrophenyl phosphate an equivalent weight of approximately 59 100 was found. From these results it was concluded that the enzyme consists of a single polypeptide chain and contains one active site per molecule. The enzyme hydrolyzed esters as well as certain aromatic amides. It also catalysed the transfer of acetyl groups to phenetidine yielding phenacetin. The activities towards aliphatic esters were much smaller. The enzyme was stable at pH values ranging from 7 to 9 and its pH-optimum was about 10. It was strongly inhibited by organophosphorous compounds, like diethyl-4-nitrophenyl phosphate or diisopropylphosphorofluoridate, as well as by physostigmine sulfate and -SH-blocking reagents, like HgCl-2 or 4-chloromercuribenzoic acid. o-Nitrophenol caused a competitive inhibition and phenetidine an uncompetitive inhibition.