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| {{STRUCTURE_1e3a| PDB=1e3a | SCENE= }} | | {{STRUCTURE_1e3a| PDB=1e3a | SCENE= }} |
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| '''A SLOW PROCESSING PRECURSOR PENICILLIN ACYLASE FROM ESCHERICHIA COLI'''
| | ===A SLOW PROCESSING PRECURSOR PENICILLIN ACYLASE FROM ESCHERICHIA COLI=== |
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| ==Overview==
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| Penicillin G acylase is a periplasmic protein, cytoplasmically expressed as a precursor polypeptide comprising a signal sequence, the A and B chains of the mature enzyme (209 and 557 residues respectively) joined by a spacer peptide of 54 amino acid residues. The wild-type AB heterodimer is produced by proteolytic removal of this spacer in the periplasm. The first step in processing is believed to be autocatalytic hydrolysis of the peptide bond between the C-terminal residue of the spacer and the active-site serine residue at the N terminus of the B chain. We have determined the crystal structure of a slowly processing precursor mutant (Thr263Gly) of penicillin G acylase from Escherichia coli, which reveals that the spacer peptide blocks the entrance to the active-site cleft consistent with an autocatalytic mechanism of maturation. In this mutant precursor there is, however, an unexpected cleavage at a site four residues from the active-site serine residue. Analyses of the stereochemistry of the 260-261 bond seen to be cleaved in this precursor structure and of the 263-264 peptide bond have suggested factors that may govern the autocatalytic mechanism.
| | The line below this paragraph, {{ABSTRACT_PUBMED_10993730}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10993730 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10993730}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hydrolysis of penicillin g acylase]] | | [[Category: Hydrolysis of penicillin g acylase]] |
| [[Category: Ntn-hydrolase]] | | [[Category: Ntn-hydrolase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:36:17 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 00:04:36 2008'' |