Esterase

About: Esterase is a research topic. Over the lifetime, 7622 publications have been published within this topic receiving 168270 citations.

Cephalosporinase and penicillinase activities of a β-lactamase from Pseudomonas pyocyanea

Abstract: 1 Pseudomonas pyocyanea NCTC 8203 produces a beta-lactamase that is inducible by high concentrations of benzylpenicillin or cephalosporin C Methicillin appeared to be a relatively poor inducer, but this could be attributed in part to its ability to mask the enzyme produced Much of the enzyme is normally cell-bound 2 No evidence was obtained that the crude enzyme preparation consisted of more than one beta-lactamase and the preparation appeared to contain no significant amount of benzylpenicillin amidase or of an acetyl esterase 3 The maximum rate of hydrolysis of cephalosporin C and several other derivatives of 7-aminocephalosporanic acid by the crude enzyme was more than five times that of benzylpenicillin Methicillin, cloxacillin, 6-aminopenicillanic acid and 7-aminocephalosporanic acid were resistant to hydrolysis, and methicillin and cloxacillin were powerful competitive inhibitors of the action of the enzyme on easily hydrolysable substrates 4 Cephalosporin C, cephalothin and cephaloridine yielded 2 equiv of acid/mole on enzymic hydrolysis, and deacetylcephalorsporin C yielded 1 equiv/mole Evidence was obtained that the opening of the beta-lactam ring of cephalosporin C and cephalothin is accompanied by the spontaneous expulsion of an acetoxy group and that of cephaloridine by the expulsion of pyridine 5 A marked decrease in the minimum inhibitory concentration of benzylpenicillin and several hydrolysable derivatives of 7-aminocephalosporanic acid was observed when the size of the inoculum was decreased This suggested that the production of a beta-lactamase contributed to the factors responsible for the very high resistance of Ps pyocyanea to these substances It was therefore concluded that the latter might show synergism with the enzyme inhibitors, methicillin and cloxacillin, against this organism

Purification and Properties of a Polyester Polyurethane-Degrading Enzyme from Comamonas acidovorans TB-35.

Abstract: A polyester polyurethane (PUR)-degrading enzyme, PUR esterase, derived from Comamonas acidovorans TB-35, a bacterium that utilizes polyester PUR as the sole carbon source, was purified until it showed a single band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This enzyme was bound to the cell surface and was extracted by addition of 0.2% N,N-bis(3-d-gluconamidopropyl)deoxycholamide (deoxy-BIGCHAP). The results of gel filtration and SDS-PAGE showed that the PUR esterase was a monomer with a molecular mass of about 62,000 Da. This enzyme, which is a kind of esterase, degraded solid polyester PUR, with diethylene glycol and adipic acid released as the degradation products. The optimum pH for this enzyme was 6.5, and the optimum temperature was 45 degrees C. PUR degradation by the PUR esterase was strongly inhibited by the addition of 0.04% deoxy-BIGCHAP. On the other hand, deoxy-BIGCHAP did not inhibit the activity when p-nitrophenyl acetate, a water-soluble compound, was used as a substrate. These observations indicated that this enzyme degrades PUR in a two-step reaction: hydrophobic adsorption to the PUR surface and hydrolysis of the ester bond of PUR.

Extremely stable and versatile carboxylesterase from a hyperthermophilic archaeon

Abstract: We have found that the hyperthermophilic archaeon Pyrobaculum calidifontis VA1 produced a thermostable esterase. We isolated and sequenced the esterase gene (estPc) from strain VA1. estPc consisted of 939 bp, corresponding to 313 amino acid residues with a molecular mass of 34,354 Da. As estPc showed significant identity (30%) to mammalian hormone-sensitive lipases (HSLs), esterase of P. calidifontis (Est) could be regarded as a new member of the HSL family. Activity levels of the enzyme were comparable or higher than those of previously reported enzymes not only at high temperature (6,410 U/mg at 90°C), but also at ambient temperature (1,050 U/mg at 30°C). The enzyme displayed extremely high thermostability and was also stable after incubation with various water-miscible organic solvents at a concentration of 80%. The enzyme also exhibited activity in the presence of organic solvents. Est of P. calidifontis showed higher hydrolytic activity towards esters with short to medium chains, with p-nitrophenyl caproate (C6) the best substrate among the p-nitrophenyl esters examined. As for the alcoholic moiety, the enzyme displayed esterase activity towards esters with both straight- and branched-chain alcohols. Most surprisingly, we found that this Est enzyme hydrolyzed the tertiary alcohol ester tert-butyl acetate, a feature very rare among previously reported lipolytic enzymes. The extreme stability against heat and organic solvents, along with its activity towards a tertiary alcohol ester, indicates a high potential for the Est of P. calidifontis in future applications.