beta-Glucosidase of Dictyostelium discoideum is inhibited by purines in the following order: adenine greater than adenosine greater than 6-methylaminopurine greater than hypoxanthine greater than inosine greater than purine greater than guanosine. Adenine inhibits activity by 50% at 1 to 2 mM. The kinetics are complex because the enzyme is stimulated by substrate and inhibited by glucose.