Purin-6-yl 6-deoxy-1-thio-beta-D-glucopyranoside (4) is a substrate for almond beta-glucosidase and a weak competitive inhibitor of bovine liver beta-D-glucuronidase (Ki approximately 20mM). Both 4 and purine-protonated 4 undergo hydrolysis catalyzed by dilute acid in the pH range 0.17-2.59. These results are compared with those previously obtained with ammonium (purin-6-yl 1-thio-beta-D-glucopyranosid)uronate, (purin-6-yl 1-thio-beta-D-glucopyranosid)uronamide, purin-6-yl 1-thio-beta-D-glucopyranoside, and purin-6-yl 2-deoxy-1-thio-beta-D-glucopyranoside, and it is concluded that the data support an involvement of substituents at C-5 in producing productive Michaelis-complex conformers. The 6-deoxyglucoside is more active than the D-glucosiduronic acid in an L1210 mouse screen.