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1gkm
From Proteopedia
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[[Image:1gkm.gif|left|200px]] | [[Image:1gkm.gif|left|200px]] | ||
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'''HISTIDINE AMMONIA-LYASE (HAL) FROM PSEUDOMONAS PUTIDA INHIBITED WITH L-CYSTEINE''' | '''HISTIDINE AMMONIA-LYASE (HAL) FROM PSEUDOMONAS PUTIDA INHIBITED WITH L-CYSTEINE''' | ||
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[[Category: Baedeker, M.]] | [[Category: Baedeker, M.]] | ||
[[Category: Schulz, G E.]] | [[Category: Schulz, G E.]] | ||
| - | [[Category: | + | [[Category: Ammonia-lyase]] |
| - | [[Category: | + | [[Category: Histidine degradation]] |
| - | [[Category: | + | [[Category: Lyase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 17:41:51 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 14:41, 2 May 2008
HISTIDINE AMMONIA-LYASE (HAL) FROM PSEUDOMONAS PUTIDA INHIBITED WITH L-CYSTEINE
Overview
Histidine ammonia-lyase (EC 4.3.1.3) catalyzes the nonoxidative elimination of the alpha-amino group of histidine using a 4-methylidene-imidazole-5-one (MIO), which is formed autocatalytically from the internal peptide segment 142Ala-Ser-Gly. The structure of the enzyme inhibited by a reaction with l-cysteine was established at the very high resolution of 1.0 A. Five active center mutants were produced and their catalytic activities were measured. Among them, mutant Tyr280-->Phe could be crystallized and its structure could be determined at 1.7 A resolution. It contains a planar sp2-hybridized 144-N atom of MIO, in contrast to the pyramidal sp3-hybridized 144-N of the wild-type. With the planar 144-N atom, MIO assumes the conformation of a putative intermediate aromatic state of the reaction, demonstrating that the conformational barrier between aromatic and wild-type states is very low. The data led to a new proposal for the geometry for the catalyzed reaction, which also applies to the closely related phenylalanine ammonia-lyase (EC 4.3.1.5). Moreover, it suggested an intermediate binding site for the released ammonia.
About this Structure
1GKM is a Single protein structure of sequence from Pseudomonas putida. Full crystallographic information is available from OCA.
Reference
Structures of two histidine ammonia-lyase modifications and implications for the catalytic mechanism., Baedeker M, Schulz GE, Eur J Biochem. 2002 Mar;269(6):1790-7. PMID:11895450 Page seeded by OCA on Fri May 2 17:41:51 2008
