GLYCOSIDASES 423 



interact satisfactorily with this pattern by appropriate translation or ro- 

 tation of the molecules (indeed, the other sides of these roughly planar 

 molecules could possibly fit the pattern in some cases). 



One of the most interesting studies of analog inhibition was reported 

 by Halvorson and Ellias (1958) for the a-glucosidase of Saccharomyces 

 italicus, the data from which are given in the accompanying tabulation. 



Several of the substances (marked by *) are also substrates; maltose, in 

 fact, is probably the natural substrate. Inversion of hydroxyl groups on 

 C-2 and C-4, and substitution or oxidation at C-6, abolish the affinity. 

 Increasing the size of the aglycone groups increases the affinity. The rather 

 potent inhibition by glucose is surprising and indicates that the alkyl agly- 

 cone groups actually reduce the affinity. This might mean that the C-1 

 hydroxyl group can be involved in the binding; a small substituent prevents 

 this but the binding increases as the alkyl group is lengthened. 



Inhibition of (3-Glucuronidases by D-Glucaro-1,4-lactone 

 and Related Compounds 



These widely distributed enzymes catalyze the hydrolysis of /5-glucur- 

 onides occurring naturally in plants and animals, and in addition may play 

 a role in mucopolysaccharide metabolism. They are not involved in the 

 glucuronide syntheses of detoxification, these reactions being catalyzed by 

 glucuronyl transferases. There is evidence that /^-glucuronidases are related 

 in some manner to growth and the activities of certain tissues, and it was 



