only glucose derivatives with a sufficiently bulky substituent in position c-2 , such as the glucokinase substrates glucose and mannose and the inhibitors mannoheptulose , glucosamine , and n-acetylglucosamine , protected glucokinase against inhibition by alloxan by binding to the active site of the enzyme .
C0017718
glucosamine
C0001056
n-acetylglucosamine