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: The two constituent subunits of the enzyme penicillin acylase from Escherichia coli strain ATCC 11105 are derived from a single precursor polypeptide by post-translational processing and the processing pathway in vivo proceeds via an intermediate comprising the alpha subunits plus endopeptide and is thus identical to the pathway which has been determined previously by in vitro analysis.
Abstract: The two constituent subunits of the enzyme penicillin acylase from Escherichia coli strain ATCC 11105 are derived from a single precursor polypeptide by post-translational processing. Mutant penicillin acylase precursors were constructed carrying insertions and deletions in various domains and they were analysed for their processing behaviour. It was found that an endopeptide region of appropriate size and an intact C-terminus were absolutely necessary for the maturation process. Internal deletions within the β-subunit domain also prevented post-translational cleavage. Processing competence, therefore, was not merely determined by the amino acid sequence in the vicinity of the processing sites but relied on a correct overall conformation of the protein. The processing pathway in vivo proceeds via an intermediate comprising the α subunits plus endopeptide and is thus identical to the pathway which has been determined previously by in vitro analysis. The post-translational modification of the precursor is probably not carried out by a specific processing enzyme(s) as the heterologous expression of the penicillin acylase (pac) structural gene yielded processed and active enzyme in different enterobacteria and in a Pseudomonas species.
82 citations
TL;DR: Despite the favourable thermodynamic conditions for the production of all beta-lactam antibiotics, low reaction rate is the basic hindrance for enzymatic synthesis of penicillins and cephalosporins having a free amino group in the acyl moiety.
82 citations
TL;DR: Mutational studies have shown that the hydrophobic core region acts in synergism with the positive charged N-terminal part of the signal peptide as a Tat recognition signal and contributes to the efficient Tat targeting of the pre-pro-penicillin amidase.
81 citations
TL;DR: Results and electrophoretic and spectroscopic analysis indicated that the denaturation was caused by partial unfolding during the depressurization step.
Abstract: The stability of the monomeric enzymes α-chymotrypsin and trypsin, and the oligomeric enzyme penicillin amidase in supercritical CO2 has been studied. They were found to be partly denatured during the depressurization step. The degree of denaturation was larger in humid CO2 than in dry CO2. Enzymes with S-S bridges (α-chymotrypsin; trypsin) were denatured to a lesser degree than the enzyme without cysteine (penicillin amidase). These results and electrophoretic and spectroscopic analysis indicated that the denaturation was caused by partial unfolding during the depressurization step.
80 citations
TL;DR: Three-dimensional structural analyses and site-directed mutagenesis studies have increased the understanding of the catalytic mechanism of these enzymes, and significant advances have been made in the resolution of racemic mixtures by means of stereoselective acylation/hydrolysis using beta-lactam acylases.
80 citations