2hhf: Difference between revisions

← Older edit Newer edit →

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

@@ Line 1: / Line 1: @@
-[[Image:2hhf.jpg|left|200px]]
+{{Seed}}
+[[Image:2hhf.png|left|200px]]
 <!--
@@ Line 9: / Line 10: @@
 {{STRUCTURE_2hhf|  PDB=2hhf  |  SCENE=  }}
-'''X-ray crystal structure of oxidized human mitochondrial branched chain aminotransferase (hBCATm)'''
+===X-ray crystal structure of oxidized human mitochondrial branched chain aminotransferase (hBCATm)===
-==Overview==
+<!--
-Mammalian branched chain aminotransferases (BCATs) have a unique CXXC center. Kinetic and structural studies of three CXXC center mutants (C315A, C318A, and C315A/C318A) of human mitochondrial (hBCATm) isozyme and the oxidized hBCATm enzyme (hBCATm-Ox) have been used to elucidate the role of this center in hBCATm catalysis. X-ray crystallography revealed that the CXXC motif, through its network of hydrogen bonds, plays a crucial role in orienting the substrate optimally for catalysis. In all structures, there were changes in the structure of the beta-turn preceding the CXXC motif when compared with wild type protein. The N-terminal loop between residues 15 and 32 is flexible in the oxidized and mutant enzymes, the disorder greater in the oxidized protein. Disordering of the N-terminal loop disrupts the integrity of the side chain binding pocket, particularly for the branched chain side chain, less so for the dicarboxylate substrate side chain. The kinetic studies of the mutant and oxidized enzymes support the structural analysis. The kinetic results showed that the predominant effect of oxidation was on the second half-reaction rather than the first half-reaction. The oxidized enzyme was completely inactive, whereas the mutants showed limited activity. Model building of the second half-reaction substrate alpha-ketoisocaproate in the pyridoxamine 5'-phosphate-hBCATm structure suggests that disruption of the CXXC center results in altered substrate orientation and deprotonation of the amino group of pyridoxamine 5'-phosphate, which inhibits catalysis.
+The line below this paragraph, {{ABSTRACT_PUBMED_17050531}}, adds the Publication Abstract to the page
+(as it appears on PubMed at http://www.pubmed.gov), where 17050531 is the PubMed ID number.
+-->
+{{ABSTRACT_PUBMED_17050531}}
 ==About this Structure==
@@ Line 20: / Line 24: @@
 ==Reference==
 Human mitochondrial branched chain aminotransferase isozyme: structural role of the CXXC center in catalysis., Yennawar NH, Islam MM, Conway M, Wallin R, Hutson SM, J Biol Chem. 2006 Dec 22;281(51):39660-71. Epub 2006 Oct 18. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17050531 17050531]
+Overexpression and characterization of the human mitochondrial and cytosolic branched-chain aminotransferases., Davoodi J, Drown PM, Bledsoe RK, Wallin R, Reinhart GD, Hutson SM, J Biol Chem. 1998 Feb 27;273(9):4982-9. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9478945 9478945]
+Cloning of the rat and human mitochondrial branched chain aminotransferases (BCATm)., Bledsoe RK, Dawson PA, Hutson SM, Biochim Biophys Acta. 1997 Apr 25;1339(1):9-13. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9165094 9165094]
 [[Category: Branched-chain-amino-acid transaminase]]
 [[Category: Homo sapiens]]
@@ Line 26: / Line 34: @@
 [[Category: Yennawar, N H.]]
 [[Category: D-aminoacid aminotransferase-like plp-dependent enzyme]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May  4 06:17:54 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 11:37:10 2008''