Synthetic reaction of Cellvibrio gilvus cellobiose phosphorylase.
The synthetic reactions of the cellobiose phosphorylase from Cellvibrio gilvus were investigated in detail. It was found that, besides D-glucose, some sugars having substitution or deletion of the hydroxyl group at C2 or C6 of the D-glucose molecule could serve as a glucosyl acceptor, though less effectively than D-glucose. The enzyme showed higher activity with beta-D-glucose than with the alpha-anomer as an acceptor. This result indicates that it recognizes the anomeric hydroxyl group not involved directly in the reaction. beta-D-Cellobiose was also phosphorolyzed faster than the alpha-anomer. Substrate inhibition was observed with D-glucose, 6-deoxy-D-glucose, or D-glucosamine as an acceptor, with D-glucose being most inhibiting. This inhibition was studied in detail and it was found that D-glucose competes with alpha-D-glucose-1-phosphate for its binding site. A model of competitive substrate inhibition was proposed, and the experimental data fit well to the theoretical values that were calculated in accordance with this model.
Kitaoka
M
M
Nippon Petrochemicals Co., Ltd., Ibaraki.
Sasaki
T
T
Taniguchi
H
H
D001667:Binding, Competitive; D003847:Deoxyglucose / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D005958:Glucosephosphates / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry; D005964:Glucosyltransferases / Q000737:chemistry*; D006088:Gram-Negative Aerobic Bacteria / Q000737:chemistry / Q000201:enzymology*; D007700:Kinetics; D013379:Substrate Specificity
D005958:Glucosephosphates; D005960:Glucosides; C006584:1,5-anhydroglucitol; D003847:Deoxyglucose; C031590:glucose-1-phosphate; D005964:Glucosyltransferases; C034714:cellobiose phosphorylase; D005947:Glucose