1spq
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Understanding protein lids: Structural analysis of active hinge mutants in triosephosphate isomerase
OverviewOverview
The conformational switch from open to closed of the flexible loop 6 of, triosephosphate isomerase (TIM) is essential for the catalytic properties, of TIM. Using a directed evolution approach, active variants of chicken, TIM with a mutated C-terminal hinge tripeptide of loop 6 have been, generated (Sun,J. and Sampson,N.S., Biochemistry, 1999, 38, 11474-11481)., In chicken TIM, the wild-type C-terminal hinge tripeptide is KTA. Detailed, enzymological characterization of six variants showed that some of these, (LWA, NPN, YSL, KTK) have decreased catalytic efficiency, whereas others, (KVA, NSS) are essentially identical with wild-type. The structural, characterization of these six variants is reported. No significant, structural differences compared with the wild-type are found for KVA, NSS, and LWA, but substantial structural adaptations are seen for NPN, YSL and, KTK. These structural differences can be understood from the buried, position of the alanine side chain in the C-hinge position 3 in the open, conformation of wild-type loop 6. Replacement of this alanine with a bulky, side chain causes the closed conformation to be favored, which correlates, with the decreased catalytic efficiency of these variants. The structural, context of loop 6 and loop 7 and their sequence conservation in 133, wild-type sequences is also discussed.
About this StructureAbout this Structure
1SPQ is a Single protein structure of sequence from Gallus gallus with PEG as ligand. Active as Triose-phosphate isomerase, with EC number 5.3.1.1 Full crystallographic information is available from OCA.
ReferenceReference
Understanding protein lids: structural analysis of active hinge mutants in triosephosphate isomerase., Kursula I, Salin M, Sun J, Norledge BV, Haapalainen AM, Sampson NS, Wierenga RK, Protein Eng Des Sel. 2004 Apr;17(4):375-82. Epub 2004 May 27. PMID:15166315
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