View source for 2nu8

[[Image:2nu8.jpg|left|200px]]

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{{STRUCTURE_2nu8|  PDB=2nu8  |  SCENE=  }} 

'''C123aT Mutant of E. coli Succinyl-CoA Synthetase'''


==Overview==
Succinyl-CoA synthetase has a highly conserved cysteine residue, Cys123alpha in the Escherichia coli enzyme, that is located near the CoA-binding site and the active-site histidine residue. To test whether the succinyl moiety of succinyl-CoA is transferred to the thiol of Cys123alpha as part of the catalytic mechanism, this residue was mutated to alanine, serine, threonine and valine. Each mutant protein was catalytically active, although less active than the wild type. This proved that the specific formation of a thioester bond with Cys123alpha is not part of the catalytic mechanism. To understand why the mutations affected catalysis, the crystal structures of the four mutant proteins were determined. The alanine mutant showed no structural changes yet had reduced activity, suggesting that the size of the cysteine is important for optimal activity. These results explain why this cysteine residue is conserved in the sequences of succinyl-CoA synthetases from different sources.

==About this Structure==
2NU8 is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2NU8 OCA]. 

==Reference==
Participation of Cys123alpha of Escherichia coli succinyl-CoA synthetase in catalysis., Hidber E, Brownie ER, Hayakawa K, Fraser ME, Acta Crystallogr D Biol Crystallogr. 2007 Aug;63(Pt 8):876-84. Epub 2007, Jul 17. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17642514 17642514]
[[Category: Escherichia coli]]
[[Category: Protein complex]]
[[Category: Fraser, M E.]]
[[Category: Atp-grasp fold]]
[[Category: Citric acid cycle]]
[[Category: Heterotetramer]]
[[Category: Ligase]]
[[Category: Rossmann fold]]
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jun  5 10:07:57 2008''