1ay0
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IDENTIFICATION OF CATALYTICALLY IMPORTANT RESIDUES IN YEAST TRANSKETOLASE
OverviewOverview
The possible roles of four histidine residues in the active site of yeast, transketolase were examined by site-directed mutagenesis. Replacement of, the invariant His69 with alanine yielded a mutant enzyme with 1.5% of the, specific activity of the wild-type enzyme and with an increased KM for the, donor. This residue is located at the bottom of the substrate cleft close, to the C1 hydroxyl group of the donor substrate, and the side chain of, His69 might be required for recognition of this hydroxyl group and, possibly for maintenance of the proper orientation of the reaction, intermediate, (alpha, beta-dihydroxyethyl)thiamin diphosphate. Amino acid, replacements of His481 by alanine, serine, and glutamine resulted in, mutant enzymes with significantly increased KM values for the donor, ... [(full description)]
About this StructureAbout this Structure
1AY0 is a [Single protein] structure of sequence from [Saccharomyces cerevisiae] with CA and TPP as [ligands]. Active as [[1]], with EC number [2.2.1.1]. Full crystallographic information is available from [OCA].
ReferenceReference
Identification of catalytically important residues in yeast transketolase., Wikner C, Nilsson U, Meshalkina L, Udekwu C, Lindqvist Y, Schneider G, Biochemistry. 1997 Dec 16;36(50):15643-9. PMID:9398292
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