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| - | [[Image:1brc.gif|left|200px]] | + | {{Seed}} |
| | + | [[Image:1brc.png|left|200px]] |
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| | {{STRUCTURE_1brc| PDB=1brc | SCENE= }} | | {{STRUCTURE_1brc| PDB=1brc | SCENE= }} |
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| - | '''RELOCATING A NEGATIVE CHARGE IN THE BINDING POCKET OF TRYPSIN'''
| + | ===RELOCATING A NEGATIVE CHARGE IN THE BINDING POCKET OF TRYPSIN=== |
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| - | ==Overview==
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| - | The functional and structural consequences of altering the position of the negatively charged aspartate residue at the base of the specificity pocket of trypsin have been examined by site-directed mutagenesis, kinetic characterization and crystallographic analysis. Anionic rat trypsin D189G/G226D exhibits a high level of catalytic activity on activated amide substrates, but its relative preference for lysine versus arginine as the P1 site residue is shifted by 30 to 40-fold in favor of lysine. The crystal structure of this variant has been determined in complexes with BPTI (bovine pancreatic trypsin inhibitor), APPI (amyloid beta-protein precursor inhibitor domain) and benzamidine inhibitors, at resolutions of 2.1 A, 2.5 A and 2.2 A, respectively. Asp226 bridges the base of the specificity pocket with its negative charge partially buried by interactions made with Ser190 and Tyr228. An equal reduction in the affinity of the variant enzyme for Arg and Lys substrates is attributable to a decreased electrostatic interaction of each ligand with the relocated aspartate residue. Comparison of structural and functional parameters with those of wild-type trypsin suggests that direct hydrogen-bonding electrostatic contacts in the S1 site do not significantly improve the free energy of substrate binding relative to indirect water-mediated interactions. The conformation adopted by Asp226, as well as by other adjacent side-chain and backbone groups, depends upon the ligand bound in the primary specificity pocket. This structural flexibility may be of critical importance to the retention of catalytic activity by the variant enzyme. | + | The line below this paragraph, {{ABSTRACT_PUBMED_8478942}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 8478942 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_8478942}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Fletterick, R J.]] | | [[Category: Fletterick, R J.]] |
| | [[Category: Perona, J J.]] | | [[Category: Perona, J J.]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:51:49 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 19:35:50 2008'' |
Revision as of 16:36, 30 June 2008
Template:STRUCTURE 1brc
RELOCATING A NEGATIVE CHARGE IN THE BINDING POCKET OF TRYPSIN
Template:ABSTRACT PUBMED 8478942
About this Structure
1BRC is a Protein complex structure of sequences from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
Relocating a negative charge in the binding pocket of trypsin., Perona JJ, Tsu CA, McGrath ME, Craik CS, Fletterick RJ, J Mol Biol. 1993 Apr 5;230(3):934-49. PMID:8478942
Page seeded by OCA on Mon Jun 30 19:35:50 2008
