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| {{STRUCTURE_1e37| PDB=1e37 | SCENE= }} | | {{STRUCTURE_1e37| PDB=1e37 | SCENE= }} |
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| '''PORCINE PANCREATIC ELASTASE COMPLEXED WITH (3S, 4S)N-PARA-NITROBENZENESULPHONYL-3-ETHYL-4-(CARBOXYLIC ACID)PYRROLIDIN-2-ONE SOAKED IN PH 9 BUFFER FOR 1 MINUTE'''
| | ===PORCINE PANCREATIC ELASTASE COMPLEXED WITH (3S, 4S)N-PARA-NITROBENZENESULPHONYL-3-ETHYL-4-(CARBOXYLIC ACID)PYRROLIDIN-2-ONE SOAKED IN PH 9 BUFFER FOR 1 MINUTE=== |
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| ==Overview==
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| beta-Lactams inhibit a range of enzymes via acylation of nucleophilic serine residues. Certain gamma-lactam analogues of monocyclic beta-lactams have also been shown to be reversible inhibitors of porcine pancreatic elastase (PPE), forming acyl-enzyme complexes that are stable with respect to hydrolysis. Crystallographic analysis at pH 5 of an acyl-enzyme complex formed with PPE and one of these inhibitors revealed the ester carbonyl located in the oxyanion hole in a similar conformation to that observed in the structure of a complex formed between a heptapeptide (beta-casomorphin-7) and PPE. Only weak electron density was observed for the His-57 side chain in its 'native' conformation. Instead, the His-57 side chain predominantly adopted a conformation rotated approx. 90 degrees from its normal position. PPE-gamma-lactam crystals were subjected to 'pH-jumps' by placing the crystals in a buffer of increased pH prior to freezing for data collection. The results indicate that the conformation of the gamma-lactam-derived acyl-enzyme species in the PPE active site is dependent on pH, a result having implications for the analysis of other serine protease-inhibitor structures at non-catalytic pH values. The results help to define the stereoelectronic relationship between the ester of the acyl-enzyme complex, the side chain of His-57 and the incoming nucleophile during the reversible (de)acylation steps, implying it is closely analogous to the hydrolytic deacylation step during catalytic peptide hydrolysis.
| | The line below this paragraph, {{ABSTRACT_PUBMED_11023818}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11023818 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11023818}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Serine protease]] | | [[Category: Serine protease]] |
| [[Category: Serine proteinase]] | | [[Category: Serine proteinase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:36:13 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 00:04:25 2008'' |