Letendre C H, Singer M F
Nucleic Acids Res. 1975 Feb;2(2):149-64. doi: 10.1093/nar/2.2.149.
The purification of polynucleotide phosphorylase from Micrococcus luteus by chromatography on phosphocellulose colums is described. This procedure offers several advantages over previous procedures. Previously determined molecular weights for Form-I enzyme and Form-T enzyme derived from Form-I by limited tryptic hydrolysis were confirmed as 2.7 and 2.3 times 10-5, respectively. Form-I appears homogeneous in the ultracentrifuge, but multiple active protein species are separable by polyacrylamide gel electrophoresis. The multiple species are probably the result of proteolysis. On polyacrylamide gel electrophoresis under denaturing conditions, Form-T yielded a single size of subunit of 71,000 daltons, and Form-I yielded several bands of different molecular sizes. These results differ from earlier determinations. The amino acid compositions of Form-I and Form-T are reported. Form-I contains only between 8 and 10 cysteine residues per molecule and Form-T half that many.
本文描述了通过磷酸纤维素柱色谱法从藤黄微球菌中纯化多核苷酸磷酸化酶的方法。该方法比以前的方法有几个优点。先前通过有限的胰蛋白酶水解从I型酶衍生的I型酶和T型酶的分子量分别确认为2.7和2.3×10⁻⁵。I型酶在超速离心中显得均一，但通过聚丙烯酰胺凝胶电泳可分离出多种活性蛋白。这些多种蛋白可能是蛋白水解的结果。在变性条件下进行聚丙烯酰胺凝胶电泳时，T型酶产生单一大小为71,000道尔顿的亚基，而I型酶产生几条不同分子大小的条带。这些结果与早期的测定不同。报道了I型酶和T型酶的氨基酸组成。I型酶每分子仅含有8至10个半胱氨酸残基，而T型酶的半胱氨酸残基数量只有I型酶的一半。
