1pnk
PENICILLIN ACYLASE HAS A SINGLE-AMINO-ACID CATALYTIC CENTRE
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OverviewOverview
Penicillin acylase (penicillin amidohydrolase, EC 3.5.1.11) is widely, distributed among microorganisms, including bacteria, yeast and, filamentous fungi. It is used on an industrial scale for the production of, 6-aminopenicillanic acid, the starting material for the synthesis of, semi-synthetic penicillins. Its in vivo role remains unclear, however, and, the observation that expression of the Escherichia coli enzyme in vivo is, regulated by both temperature and phenylacetic acid has prompted, speculation that the enzyme could be involved in the assimilation of, aromatic compounds as carbon sources in the organism's free-living mode., The mature E. coli enzyme is a periplasmic 80K heterodimer of A and B, chains (209 and 566 amino acids, respectively) synthesized as a single, cytoplasmic precursor containing a 26-amino-acid signal sequence to direct, export to the cytoplasm and a 54-amino-acid spacer between the A and B, chains which may influence the final folding of the chains. The N-terminal, serine of the B chain reacts with phenylmethylsulphonyl fluoride, which is, consistent with a catalytic role for the serine hydroxyl group. Modifying, this serine to a cysteine inactivates the enzyme, whereas threonine, arginine or glycine substitution prevents in vivo processing of the, enzyme, indicating that this must be an important recognition site for, cleavage. Here we report the crystal structure of penicillin acylase at, 1.9 A resolution. Our analysis shows that the environment of the, catalytically active N-terminal serine of the B chain contains no adjacent, histidine equivalent to that found in the serine proteases. The nearest, base to the hydroxyl of this serine is its own alpha-amino group, which, may act by a new mechanism to endow the enzyme with its catalytic, properties.
About this StructureAbout this Structure
1PNK is a Protein complex structure of sequences from Escherichia coli with CA as ligand. Active as Penicillin amidase, with EC number 3.5.1.11 Full crystallographic information is available from OCA.
ReferenceReference
Penicillin acylase has a single-amino-acid catalytic centre., Duggleby HJ, Tolley SP, Hill CP, Dodson EJ, Dodson G, Moody PC, Nature. 1995 Jan 19;373(6511):264-8. PMID:7816145
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