Hamamoto T, Okuyama K, Noguchi T, Midorikawa Y
Research & Development Division, Yamasa Corporation, Chiba, Japan.
Biosci Biotechnol Biochem. 1997 Feb;61(2):272-5. doi: 10.1271/bbb.61.272.
Bacillus stearothermophilus TH 6-2 has two kinds of purine nucleoside phosphorylases (Pu-NPase I and Pu-NPase II). The Pu-NPase I is a functional homolog of eukaryotic purine nucleoside phosphorylases that can catalyze the phosphorolysis of inosine and guanosine, but not adenosine, the primary substrate of Pu-NPase II. The Pu-NPase I gene of TH 6-2 has been cloned, sequenced, and expressed in E. coli. The gene corresponded to an open reading frame of 822 nucleotides that translates into a putative 274-amino acid protein with a molecular weight of 29,637. The deduced amino terminus sequence completely coincided with that found for the purified enzyme. The cloned gene was overexpressed in E. coli by using the trc promoter to produce an active enzyme in large quantities. The amino acid sequence of Pu-NPase I shared 50% similarity with those of human and mouse purine nucleoside phosphorylases.
嗜热脂肪芽孢杆菌TH 6-2有两种嘌呤核苷磷酸化酶（嘌呤核苷磷酸化酶I和嘌呤核苷磷酸化酶II）。嘌呤核苷磷酸化酶I是真核嘌呤核苷磷酸化酶的功能同源物，可催化肌苷和鸟苷的磷酸解，但不能催化腺苷（嘌呤核苷磷酸化酶II的主要底物）的磷酸解。已克隆、测序了TH 6-2的嘌呤核苷磷酸化酶I基因，并在大肠杆菌中进行了表达。该基因对应于一个822个核苷酸的开放阅读框，可翻译成一个推定的274个氨基酸的蛋白质，分子量为29,637。推导的氨基末端序列与纯化酶的序列完全一致。通过使用trc启动子，克隆基因在大肠杆菌中过量表达，以大量产生活性酶。嘌呤核苷磷酸化酶I的氨基酸序列与人和小鼠嘌呤核苷磷酸化酶的序列有50%的相似性。
