Tan L U, Mackenzie R E
Biochim Biophys Acta. 1977 Nov 23;485(1):52-9. doi: 10.1016/0005-2744(77)90192-9.
Tryptic digestion of a multifunctional enzyme from porcine liver containing methylenetetrahydrofolate dehydrogenase (5,10-methylenetetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.5), methenyltetrahydrofolate cyclohydrolase (5,10-methenyltetrahydrofolate 5-hydrolase, EC 3.5.4.9) and formyltetrahydrofolate synthetase (formate:tetrahydrofolate ligase, EC 6.3.4.3) activities destroys the synthetase. A fragment containing both dehydrogenase and cyclohydrolase activities has been isolated by affinity chromatography on an NADP+-Sepharose affinity column. The purified fragment is homogeneous on dodecyl sulfate-polyacrylamide gel electrophoresis where its molecular weight was determined as 33 000 +/- 1200 compared with 100 000 for the undigested protein. The cyclohydrolase activity retains sensitivity to inhibition by NADP+, MgATP and ATP.
用胰蛋白酶消化猪肝中的一种多功能酶，该酶含有亚甲基四氢叶酸脱氢酶（5,10 - 亚甲基四氢叶酸：NADP +氧化还原酶，EC 1.5.1.5）、次甲基四氢叶酸环水解酶（5,10 - 次甲基四氢叶酸5 - 水解酶，EC 3.5.4.9）和甲酰四氢叶酸合成酶（甲酸：四氢叶酸连接酶，EC 6.3.4.3）活性，会破坏合成酶。通过在NADP + - 琼脂糖亲和柱上进行亲和层析，分离出了一个同时含有脱氢酶和环水解酶活性的片段。纯化后的片段在十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳上呈均一状态，与未消化的蛋白质分子量100000相比，其分子量测定为33000±1200。环水解酶活性对NADP +、MgATP和ATP的抑制仍保持敏感。
