Cooperative Inhibition of Human Thymidylate Synthase by Mixtures of Active Site Binding and Allosteric Inhibitors.
From: Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA.
Biochemistry
- Publish Date: Mar 2007
- ISSN: 0006-2960
- Volume: 46
- Issue: 10
- Pages: 2823-30
- Medium: Print
- Language: English
- Citation (JAMA): Lovelace Leslie L, Gibson Lydia M, Lebioda Lukasz, et al. Cooperative Inhibition of Human Thymidylate Synthase by Mixtures of Active Site Binding and Allosteric Inhibitors.. Biochemistry Mar 2007;46:2823-30
Abstract
Thymidylate synthase (TS) is a target in the chemotherapy of colorectal cancer and some other neoplasms. It catalyzes the transfer of a methyl group from methylenetetrahydrofolate to dUMP to form dTMP. On the basis of structural considerations, we have introduced 1,3-propanediphosphonic acid (PDPA) as an allosteric inhibitor of human TS (hTS); it is proposed that PDPA acts by stabilizing an inactive conformer of loop 181-197. Kinetic studies showed that PDPA is a mixed (noncompetitive) inhibitor versus dUMP. In contrast, versus methylenetrahydrofolate at concentrations lower than 0.25 microM, PDPA is an uncompetitive inhibitor, while at PDPA concentrations higher than 1 microM the inhibiton is noncompetive, as expected. At the concentrations corresponding to uncompetitive inhibition, PDPA shows positive cooperativity with an antifolate inhibitor, ZD9331, which binds to the active conformer. PDPA binding leads to the formation of hTS tetramers, but not higher oligomers. These data are consistent with a model in which hTS exists preferably as an asymmetric dimer with one subunit in the active conformation of loop 181-197 and the other in the inactive conformation.
Mesh Headings (Keywords): Allosteric Regulation, Animals, Binding Sites, Fluorescence, Humans, Kinetics, Mice, Models, Molecular, Phosphates, Phosphonic Acids, Pregnadienes, Protein Conformation, Quinazolines, Thymidylate Synthase
Check for Full Text / PubMed Unique Identifier (PMID): 17297914
This abstract is part of PubMed, a service of the U.S. National Library of Medicine. PubMed includes more than 17 million citations from MEDLINE and other life science journals for biomedical articles. See Copyright and Disclaimers.
Linked medical terms appearing on this page are added by Healia to help readers find more information and are not part of the original PubMed document.
The data herein was last updated on July 8th, 2008 and may not reflect the most current and accurate data available from NLM.