Preparation and Properties of 5'-Nucleotidase from Smooth Muscle of Small Intestine

Abstract 5'-Nucleotidase prepared from smooth muscle is strongly inhibited by ADP. This inhibition is much stronger than the previously described inhibition of 5'-nucleotidase by ATP. The α,β-methylenephosphonate analogue of ADP is an exceptionally powerful inhibitor of the enzyme. The enzyme possesses three pH optima. The lowest of these optima is observed only when the enzyme is not inhibited by buffer anions; the highest is observed only in the presence of magnesium ions.