Triton-stimulated nucleoside diphosphatase: Characterization

Summary Our previous report indicated a Triton-stimulated NDPase was specifically associated with Golgi membranes isolated from corn roots. Characterization of the enzyme indicates that UDP is the slightly preferred substrate with Mn²⁺ the preferred divalent cation. Monovalent cations do not further activate the Triton-stimulated UDPase activity. The enzyme has a pH optimum at 6.5 and a temperature optimum between 38–40°C. Kinetic analyses indicate that UDP-Mn²⁺ is the substrate for the enzyme.Properties of the Triton-stimulated NDPase are compared to other membrane associated NDPases isolated from plants, animals and fungi. Characteristics and subcellular location of NDPase activity are discussed in relation to the possible biochemical role of the enzyme.This research was supported in part by National Science Foundation grant CDP 79-7927121 and funds provided by Bronfman Science Center, Williams College.