Evidence for the essential histidine residue at the active site of glucose/xylose isomerase from Streptomyces.
Modification of glucose/xylose isomerase from Streptomyces sp. NCIM 2730 by diethylpyrocarbonate (DEPC) or its photo-oxidation in presence of rose bengal or methylene blue caused rapid loss in its activity. The inactivation of the enzyme was accompanied by an increase in the absorbance at 240 nm and was reversed by hydroxylamine. Glucose and xylose but not Mg++ and Co++ afforded significant protection to the enzyme from inactivation by DEPC. Inactivation followed pseudo-first-order kinetics and modification of a single histidine residue per mole of enzyme was indicated.
Division of Biochemical Sciences, National Chemical Laboratory, Pune, India.
S M
SM
Gaikwad
M W
MW
More
H G
HG
Vartak
V V
VV
Deshpande
D019747:Aldose-Ketose Isomerases; D001665:Binding Sites; D002238:Carbohydrate Epimerases / Q000378:metabolism*; D002384:Catalysis; D004047:Diethyl Pyrocarbonate; D004789:Enzyme Activation / Q000187:drug effects; D006639:Histidine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008751:Methylene Blue; D010084:Oxidation-Reduction; D012395:Rose Bengal; D013302:Streptomyces / Q000201:enzymology*; D014443:Tyrosine / Q000378:metabolism
D012395:Rose Bengal; D014443:Tyrosine; D006639:Histidine; D002238:Carbohydrate Epimerases; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase; D004047:Diethyl Pyrocarbonate; D008751:Methylene Blue