Alpha-3-ketoglucosidase of Agrobacterium tumefaciens.
A 3-ketosucrose-degrading enzyme was purified 80-fold from the sonic extracts of Agrobacterium tumefaciens IAM 1525 grown on a sucrose-containing medium. The enzyme catalyzes hydrolysis of alpha-3-ketoglucosides such as 3-ketosucrose, 3-ketotrehalose, 3-ketomaltose, and 3-ketoglucose-1-phosphate but not of beta-3-ketoglucosides, beta-3-ketogalactosides, and other glycosides such as sucrose, trehalose, maltose, glucose-1-phosphate, cellobiose, lactose, or raffinose. From the strict substrate specificity of this enzyme, the name alpha-d-3-ketoglucoside 3-ketoglucohydrolase (trivial name, alpha-3-ketoglucosidase) was proposed. K(m) values for 3-ketosucrose and 3-ketotrehalose were 3.9 x 10(-3)m and 4.8 x 10(-3)m, respectively. Optimum pH was 8.0 to 8.3. 3-Ketoglucose, a reaction product from alpha-3-ketoglucosides by the enzyme, behaved as a strong inhibitor. Physiological significance of this enzyme in the disaccharide metabolism of this bacterium was discussed.
D002247:Carbon Isotopes; D002848:Chromatography, DEAE-Cellulose; D002854:Chromatography, Paper; D003124:Colorimetry; D004187:Disaccharides / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005959:Glucosidases / Q000032:analysis / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds; D012231:Rhizobium / Q000201:enzymology*; D013053:Spectrophotometry; D013395:Sucrose / Q000378:metabolism; D013431:Sulfates; D014465:Ultrasonics
D002247:Carbon Isotopes; D004187:Disaccharides; D000644:Quaternary Ammonium Compounds; D013431:Sulfates; D013395:Sucrose; D005954:Glucosephosphate Dehydrogenase; D005959:Glucosidases