Topic
Penicillin amidase
About: Penicillin amidase is a research topic. Over the lifetime, 576 publications have been published within this topic receiving 15563 citations. The topic is also known as: penicillin amidohydrolase & ampicillin acylase.
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TL;DR: Penicillin G acylase from Proteus rettgeri is an 80-000- to 90,000-dalton enzyme composed of two nonidentical subunits that imparts specificity for the penicillin side chain.
Abstract: Penicillin G acylase from Proteus rettgeri is an 80,000- to 90,000-dalton enzyme composed of two nonidentical subunits. Both subunits were required for enzymatic activity. The 65,000-dalton beta subunit contained a phenylmethylsulfonyl fluoride-sensitive residue required for enzymatic activity, and the 24,500-dalton alpha subunit contained the domain that imparts specificity for the penicillin side chain.
54 citations
TL;DR: The integrated effect of additional chemical modification plus previous multipoint covalent attachment has allowed us to prepare PGA derivatives which are 50,000 more thermostable than native PGA as well as most of the commercial P GA derivatives.
54 citations
TL;DR: In this “aqueous solution–precipitate” system, accumulation of both products, ampicillin and d -(−)-phenylglycine, proceeds through the formation of their supersaturated solutions, which positively influences the efficiency of the biocatalytic process.
Abstract: Penicillin acylase-catalyzed ampicillin synthesis via acyl group transfer in aqueous solution is highly dependent on the initial substrate concentration. The solubility of one substrate, 6-aminopenicillanic acid (6-APA), can be advantageously enhanced by the presence of acyl donor, the second substrate. Furthermore, a comparison of enzymatic synthesis in homogeneous solution with synthesis in a heterogeneous system having partially undissolved reactants, reveals major advantages for the latter approach. In this “aqueous solution–precipitate” system, accumulation of both products, ampicillin and d -(−)-phenylglycine, proceeds through the formation of their supersaturated solutions. Subsequent precipitation of the product ampicillin positively influences the efficiency of the biocatalytic process. As a result, ampicillin synthesis proceeds in 93% conversion on 6-APA and in 60% conversion on d -(−)-phenylglycine methyl ester.
54 citations
TL;DR: Native and immobilized preparations of penicillin acylase from Escherichia coli and Alcaligenes faecalis were studied using an active site titration technique and a loss of active sites as well as a decrease of catalytic activity per active site was observed upon immobilization.
Abstract: Native and immobilized preparations of penicillin acylase from Escherichia coli and Alcaligenes faecalis were studied using an active site titration technique. Knowledge of the number of active sites allowed the calculation of the average turnover rate of the enzyme in the various preparations and allowed us to quantify the contribution of irreversible inactivation of the enzyme to the loss of catalytic activity during the immobilization procedure. In most cases a loss of active sites as well as a decrease of catalytic activity per active site (turnover rate) was observed upon immobilization. Immobilization techniques affected the enzymes differently. The effect of increased loading of penicillin acylase on the average turnover rate was determined by active site titration to assess diffusion limitations in the carrier.
53 citations
TL;DR: Accumulation of PA precursor protein suggests that postranslational processing and translocation through the cytoplasmic membrane limit PA production.
53 citations