| Abstract: | The presence and some properties of an NAD+ transport system were examined in PA5, a Mg, Ca-ATPase EC 3.6.1.3]-defective mutant strain of Escherichia coli W2252. NAD+ uptake was stimulated by exogenous energy sources and dependent on external substrate concentrations with an apparent Km of about 25 micrometer. Most of the radioactivity from 14C]-NAD+ accumulated in the cells was identified as NAD+. 14C]NAD+ uptake was competively inhibited by unlabeled NAD+, NADP+, NMN+ or nicotinamide. Similar uptake activity was also observed in W2252. |
