1e3r: Difference between revisions
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'''CRYSTAL STRUCTURE OF KETOSTEROID ISOMERASE MUTANT D40N (D38N TI NUMBERING) FROM PSEUDOMONAS PUTIDA COMPLEXED WITH ANDROSTEN-3BETA-OL-17-ONE''' | '''CRYSTAL STRUCTURE OF KETOSTEROID ISOMERASE MUTANT D40N (D38N TI NUMBERING) FROM PSEUDOMONAS PUTIDA COMPLEXED WITH ANDROSTEN-3BETA-OL-17-ONE''' | ||
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[[Category: Kim, M S.]] | [[Category: Kim, M S.]] | ||
[[Category: Oh, B H.]] | [[Category: Oh, B H.]] | ||
[[Category: | [[Category: Androsten-3beta-ol-17-one]] | ||
[[Category: | [[Category: Ksi ketosteroied isomerase]] | ||
[[Category: | [[Category: Lbhb]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:37:41 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 14:37, 2 May 2008
CRYSTAL STRUCTURE OF KETOSTEROID ISOMERASE MUTANT D40N (D38N TI NUMBERING) FROM PSEUDOMONAS PUTIDA COMPLEXED WITH ANDROSTEN-3BETA-OL-17-ONE
OverviewOverview
Delta(5)-3-Ketosteroid isomerase catalyzes cleavage and formation of a C-H bond at a diffusion-controlled limit. By determining the crystal structures of the enzyme in complex with each of three different inhibitors and by nuclear magnetic resonance (NMR) spectroscopic investigation, we evidenced the ionization of a hydroxyl group (pK(a) approximately 16.5) of an inhibitor, which forms a low barrier hydrogen bond (LBHB) with a catalytic residue Tyr(14) (pK(a) approximately 11.5), and the protonation of the catalytic residue Asp(38) with pK(a) of approximately 4.5 at pH 6.7 in the interaction with a carboxylate group of an inhibitor. The perturbation of the pK(a) values in both cases arises from the formation of favorable interactions between inhibitors and catalytic residues. The results indicate that the pK(a) difference between catalytic residue and substrate can be significantly reduced in the active site environment as a result of the formation of energetically favorable interactions during the course of enzyme reactions. The reduction in the pK(a) difference should facilitate the abstraction of a proton and thereby eliminate a large fraction of activation energy in general acid/base enzyme reactions. The pK(a) perturbation provides a mechanistic ground for the fast reactivity of many enzymes and for the understanding of how some enzymes are able to extract a proton from a C-H group with a pK(a) value as high as approximately 30.
About this StructureAbout this Structure
1E3R is a Single protein structure of sequence from Pseudomonas putida. Full crystallographic information is available from OCA.
ReferenceReference
Detection of large pKa perturbations of an inhibitor and a catalytic group at an enzyme active site, a mechanistic basis for catalytic power of many enzymes., Ha NC, Kim MS, Lee W, Choi KY, Oh BH, J Biol Chem. 2000 Dec 29;275(52):41100-6. PMID:11007792 Page seeded by OCA on Fri May 2 14:37:41 2008