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'''LEUCINE DEHYDROGENASE FROM BACILLUS SPHAERICUS''' | '''LEUCINE DEHYDROGENASE FROM BACILLUS SPHAERICUS''' | ||
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[[Category: Stillman, T J.]] | [[Category: Stillman, T J.]] | ||
[[Category: Turnbull, A P.]] | [[Category: Turnbull, A P.]] | ||
[[Category: | [[Category: Oxidoreductase]] | ||
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Revision as of 20:50, 2 May 2008
LEUCINE DEHYDROGENASE FROM BACILLUS SPHAERICUS
Overview
BACKGROUND: Glutamate, phenylalanine and leucine dehydrogenases catalyze the NAD(P)(+)-linked oxidative deamination of L-amino acids to the corresponding 2-oxoacids, and sequence homology between these enzymes clearly indicates the existence of an enzyme superfamily related by divergent evolution. We have undertaken structural studies on a number of members of this family in order to investigate the molecular basis of their differential amino acid specificity. RESULTS: We have solved the X-ray structure of the leucine dehydrogenase from Bacillus sphaericus to a resolution of 2.2 A. Each subunit of this octameric enzyme contains 364 amino acids and folds into two domains, separated by a deep cleft. The nicotinamide ring of the NAD+ cofactor binds deep in this cleft, which is thought to close during the hydride transfer step of the catalytic cycle. CONCLUSIONS: Comparison of the structure of leucine dehydrogenase with a hexameric glutamate dehydrogenase has shown that these two enzymes share a related fold and possess a similar catalytic chemistry. A mechanism for the basis of the differential amino acid specificity between these enzymes involves point mutations in the amino acid side-chain specificity pocket and subtle changes in the shape of this pocket caused by the differences in quaternary structure.
About this Structure
1LEH is a Single protein structure of sequence from Lysinibacillus sphaericus. Full crystallographic information is available from OCA.
Reference
A role for quaternary structure in the substrate specificity of leucine dehydrogenase., Baker PJ, Turnbull AP, Sedelnikova SE, Stillman TJ, Rice DW, Structure. 1995 Jul 15;3(7):693-705. PMID:8591046 Page seeded by OCA on Fri May 2 23:50:43 2008
