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Catabolism of NAD+ in rabbit reticulocyte lysates

1978; Elsevier BV; Volume: 520; Issue: 3 Linguagem: Inglês

10.1016/0005-2787(78)90144-2

1879-3002

Joseph Wu, Michael B. Lennon, Robert J. Suhadolnik,

Pancreatic function and diabetes

Abstract NAD+ catabolism in rabbit reticulocyte lysates has been studied using [adenine-14C]-, [carbonyl-14C]- and [pyrophosphate-32P]NAD+. NAD+ is rapidly and quantitatively converted to ATP and ribose 5-phosphate. The ATP is formed via ADPribose. NAD+ glycohyrolase (NADase), ADPribose pyrophosphatase, adenylate and/or phosphoglycerate kinase, and pyruvate kinase are essential in the conversion of NAD+ to ATP. This is based on the following four experiments. First, theobromine and nicotinamide, inhibitors of NADase, prevent the conversion of NAD+ to ATP. Exogenously supplied NADase results in the accumulation of ADPribose in 1–2 min. The ADPribose is then rapidly converted to ATP. Second, incubation of NAD+ with dialyzed lysate results in the accumulation of AMP. Third, in the presence of P1,P5-di(adenosine-5′)-pentaphosphate, an inhibitor of adenylate kinase, the decrease in ATP formation parallels the increase in AMP. Fourth, [pyrophosphate-32P]NAD+ is converted to [32P]ATP and ribose 5-[32P]phosphate. The ribose 5-[32P]phosphate formed from the catabolism of [pyrophosphate-32P]NAD+ is not further utilized in these lysate preparations. The hydrolysis of NAD+ and ADPribose is catalyzed by NAD+ glycohydrolase and ADPribose pyrophosphatase. These two enzymes have been resolved by Sephadex G-100 gel filtration and have distinctly different (i) pH profiles (ii) temperature-activity profiles and (iii) activities with NAD+ analogs.