3ypi | pdb_00003ypi

ELECTROPHILIC CATALYSIS IN TRIOSEPHOSPHASE ISOMERASE: THE ROLE OF HISTIDINE-95

spinqualitylabelsall models 3ypi, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3ypi is a 2 chain structure with sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: PGH Activity: Triose-phosphate isomerase, with EC number 5.3.1.1 Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Electrophilic catalysis by histidine-95 in triosephosphate isomerase has been probed by using Fourier transform infrared spectroscopy and X-ray crystallography. The carbonyl stretching frequency of dihydroxyacetone phosphate bound to the wild-type enzyme is known to be 19 cm-1 lower (at 1713 cm-1) than that of dihydroxyacetone phosphate free in solution (at 1732 cm-1), and this decrease in stretching frequency has been ascribed to an enzymic electrophile that polarizes the substrate carbonyl group toward the transition state for the enolization. Infrared spectra of substrate bound to two site-directed mutants of yeast triosephosphate isomerase in which histidine-95 has been changed to glutamine or to asparagine show unperturbed carbonyl stretching frequencies between 1732 and 1742 cm-1. The lack of carbonyl polarization when histidine-95 is removed suggests that histidine-95 is indeed the catalytic electrophile, at least for dihydroxyacetone phosphate. Kinetic studies of the glutamine mutant (H95Q) have shown that the enzyme follows a subtly different mechanism of proton transfers involving only a single acid-base catalytic group. These findings suggest an additional role for histidine-95 as a general acid-base catalyst in the wild-type enzyme. The X-ray crystal structure of the H95Q mutant with an intermediate analogue, phosphoglycolohydroxamate, bound at the active site has been solved to 2.8-A resolution, and this structure clearly implicates glutamate-165, the catalytic base in the wild-type isomerase, as the sole acid-base catalyst for the mutant enzyme.(ABSTRACT TRUNCATED AT 250 WORDS) Electrophilic catalysis in triosephosphate isomerase: the role of histidine-95.,Komives EA, Chang LC, Lolis E, Tilton RF, Petsko GA, Knowles JR Biochemistry. 1991 Mar 26;30(12):3011-9. PMID:2007138 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Triose Phosphate Isomerase

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