Purification and properties of purine nucleoside phosphorylase from Brevibacterium acetylicum ATCC 954.
作者:Hideyuki SHIRAE、Kenzo YOKOZEKI
DOI:10.1271/bbb1961.55.493
日期:——
Purine nucleoside phosphorylase of Brevibacterium acetylicum ATCC 954, which catalyzes the production of ribavirin (1-β-D-ribofuranosyl-1, 2, 4-triazole-3-carboxamide), a potent antiviral agent, from purine nucleoside and 1, 2, 4-triazole-3-carboxamide in a high yield, was purified 49-fold. This enzyme had a molecular weight of 31, 000 and was a monomer. The isoelectric point of the enzyme was 4.7. The optimal temperature and pH of inosine phosphorolyzing reaction catalyzed by the enzyme was around 8.5 and 70°C, respectively. The Michaelis constants for inosine, guanosine, and ribavirin were 1.43 mM, 2.44 mM and 2.08 mM, respectively, at 40°C. This enzyme appeared to be a SH enzyme because it was inactivated by SH reagents, p-chloromercuribenzoate and N-ethylmaleimide, and HgCl2. In addition, this enzyme was completely inactivated by AgNO3 and was slightly inhibited by CuSO4. It showed nucleoside-phosphorolyzing activity toward inosine, 2'-deoxyinosine, 2', 3'-dideoxyinosine, guanosine, 2'-deoxyguanosine, and xanthosine. However, adenosine and its derivatives could not be phosphorolyzed. This enzyme could not also phosphorolyze various 5'-mononucleotides. According to the amino terminal sequence analysis, the twenty residues from the amino terminal end of this enzyme were identified as follows: MTVNWNETRS-FLECKMQAKPE.
Brevibacterium acetylicum ATCC 954 的嘌呤核苷磷酸化酶能够以高产率催化从嘌呤核苷和 1, 2, 4-三氮唑-3-羧酰胺生成强效抗病毒剂利巴韦林(1-β-D-核糖苷-1, 2, 4-三氮唑-3-羧酰胺),其已被纯化49倍。该酶的分子量为31,000,属于单体。该酶的等电点为4.7。该酶催化的肌苷磷酸水解反应的最佳温度和pH分别为约70°C和8.5。肌苷、鸟苷和利巴韦林的米氏常数分别为1.43 mM、2.44 mM和2.08 mM(在40°C下)。该酶似乎是一种SH酶,因为它被SH试剂、对氯汞苯甲酸酯和N-乙基马来酰亚胺以及HgCl2失活。此外,该酶被AgNO3完全失活,并且对CuSO4有轻微抑制作用。它对肌苷、2'-去氧肌苷、2', 3'-二脱氧肌苷、鸟苷、2'-去氧鸟苷和黄苷显示出核苷磷酸化活性。然而,腺苷及其衍生物不能被磷酸化。该酶也无法磷酸化各种5'-单核苷酸。根据氨基端序列分析,这个酶的氨基端20个残基被确认为:MTVNWNETRS-FLECKMQAKPE。