Foster J W
J Bacteriol. 1981 Feb;145(2):1002-9. doi: 10.1128/jb.145.2.1002-1009.1981.
Extracts of Salmonella typhimurium were chromatographed by using Sephadex G-150 to separate the various enzymes involved with pyridine nucleotide cycle metabolism. This procedure revealed a previously unsuspected nicotinamide adenine dinucleotide (NAD) glycohydrolase (EC 3.2.2.5) activity, which was not observed in crude extracts. In contrast to NAd glycohydrolase, NAD pyrophosphatase (EC 3.6.1.22) was readily measured in crude extracts. This enzyme possessed a native molecular weight of 120,000. Other enzymes examined included nicotinamide mononucleotide (NMN) deamidase (EC 3.5.1.00), molecular weight of 43,000; NMN glycohydrolase (EC 3.2.2.14), molecular weight of 67,000; nicotinic acid phosphoribosyl transferase (EC 2.4.2.11), molecular weight of 47,000; and nicotinamide deamidase (EC 3.5.1.19), molecular weight of 35,000. NMN deamidase and NMN glycohydrolase activities were both examined for end product repression by measuring their activities in crude extracts prepared from cells grown with and without 10(-5) M nicotinic acid. No repression was observed with either activity. Both activities were also examined for feedback inhibition by NAD, reduced NAD, and NADP. NMN deamidase was unaffected by any of the compounds tested. NMN glycohydrolase was greatly inhibited by NAD and reduced NAD, whereas NADP was much less effective. Inhibition of NMN glycohydrolase was found to level off at an NAD concentration of ca. 1 mN, the approximate intracellular concentration of NAD.
使用葡聚糖凝胶G - 150对鼠伤寒沙门氏菌提取物进行色谱分析，以分离参与吡啶核苷酸循环代谢的各种酶。该程序揭示了一种以前未被怀疑的烟酰胺腺嘌呤二核苷酸（NAD）糖水解酶（EC 3.2.2.5）活性，在粗提物中未观察到这种活性。与NAD糖水解酶相反，NAD焦磷酸酶（EC 3.6.1.22）在粗提物中很容易检测到。这种酶的天然分子量为120,000。检测的其他酶包括烟酰胺单核苷酸（NMN）脱酰胺酶（EC 3.5.1.00），分子量为43,000；NMN糖水解酶（EC 3.2.2.14），分子量为67,000；烟酸磷酸核糖基转移酶（EC 2.4.2.11），分子量为47,000；以及烟酰胺脱酰胺酶（EC 3.5.1.19），分子量为35,000。通过测量在添加和不添加10^(-5) M烟酸培养的细胞制备的粗提物中的活性，检测了NMN脱酰胺酶和NMN糖水解酶的终产物阻遏作用。未观察到任何一种活性受到阻遏。还检测了这两种活性是否受到NAD、还原型NAD和NADP的反馈抑制。NMN脱酰胺酶不受所测试的任何化合物的影响。NMN糖水解酶受到NAD和还原型NAD的强烈抑制，而NADP的抑制作用则小得多。发现NMN糖水解酶的抑制作用在NAD浓度约为1 mN时趋于平稳，这大约是细胞内NAD的浓度。
