期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1979
卷号：76
期号：2
页码：750-754
DOI：10.1073/pnas.76.2.750
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Thymidylate synthetase (5,10-methylenetetrahydrofolate:dUMP C-methyltransferase, EC 2.1.1.45 ) from a human leukemic cell line has been purified to homogeneity with one-step affinity column chromatography. The purified enzyme has a specific activity of 3.8 micron/min per mg of protein, which corresponds to a turnover number of 250. These are the highest values reported for a thymidylate synthetase from neoplastic tissue. A ratio of 1.7 mol of 5-fluoro-2'-deoxyuridylate binds per mol of enzyme in the presence of 5,10-methylenetetrahydrofolate. The ternary complex so formed migrates intact on denaturing gels and can be precipitated with trichloroacetic acid; however, urea dissociates the ternary complex. The human thymidylate synthetase is composed of two subunits of 33,000 daltons each. It contains more residues of cysteine, glycine, and arginine and fewer of histidine than the well-studied thymidylate synthetase from Lactobacillus casei.
