Ueda K, Fukushima M, Okayama H, Hayaishi O
J Biol Chem. 1975 Oct 10;250(19):7541-6.
A new type of nicotinamide adenine dinucleotide glycohydrolase (NADase) has been isolated from rat liver nuclei. When partially purified chromatin is passed through a Sephadex G-200 column in the presence of 1 M NaCl, enzyme activities catalyzing the liberation of nicotinamide from NAD elute in two peaks. One, which appears in the void volume fraction, hydrolyzes the nicotinamide-ribose linkage of NAD to produce nicotinamide and ADP-ribose in stoichiometric amounts. This activity is not inhibited by 5 mM nicotinamide. The other, which elutes much later, catalyzes the formation of poly(ADP-ribose) from NAD and is completely inhibited by 5 mM nicotinamide. The former, NADase, is DNase-insensitive and thermostable, has a pH optimum of 6.5 to 7, a Km for NAD of 28 muM, and a Ki for nicotinamide of 80 mM, and hydrolyzes NADP as well as NAD. The latter, poly(ADP-ribose) synthetase, is sensitive to DNase treatment and heat labile, has a pH optimum of 8 to 8.5, a Km for NAD of 250 muM and a Ki for nicotinamide of 0.5 mM and is strictly specific for NAD. Further, the former NADase is shown to lack transglycosidase activity, which has been documented to be a general property of NADases derived from animal tissues. These results indicate that the NAD-hydrolyzing enzyme newly isolated from nuclei is a novel type of mammalian NADase which catalyzes the hydrolytic cleavage of the nicotinamide-ribose linkage of NAD.
一种新型烟酰胺腺嘌呤二核苷酸糖水解酶（NADase）已从大鼠肝细胞核中分离出来。当部分纯化的染色质在1 M氯化钠存在下通过葡聚糖G - 200柱时，催化从NAD中释放烟酰胺的酶活性以两个峰洗脱。一个出现在空体积部分，水解NAD的烟酰胺 - 核糖键，以化学计量的量产生烟酰胺和ADP - 核糖。该活性不受5 mM烟酰胺的抑制。另一个洗脱时间要晚得多，催化从NAD形成聚（ADP - 核糖），并被5 mM烟酰胺完全抑制。前者，即NADase，对DNase不敏感且耐热，最适pH为6.5至7，对NAD的Km为28 μM，对烟酰胺的Ki为80 mM，并且能水解NADP以及NAD。后者，聚（ADP - 核糖）合成酶，对DNase处理敏感且热不稳定，最适pH为8至8.5，对NAD的Km为250 μM，对烟酰胺的Ki为0.5 mM，并且严格对NAD具有特异性。此外，已证明前者NADase缺乏转糖苷酶活性，而转糖苷酶活性已被证明是源自动物组织的NADase的一般特性。这些结果表明，新从细胞核中分离出的NAD水解酶是一种新型的哺乳动物NADase，它催化NAD的烟酰胺 - 核糖键的水解裂解。
