Interaction of 5-fluoro-4-thio-2'-deoxyuridine 5'-phosphate with mammalian tumour thymidylate synthase: role of the pyrimidine N(3)-H dissociation.
Biochem Biophys Res Commun
; 149(3): 1200-7, 1987 Dec 31.
Article
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| MEDLINE
| ID: mdl-3480707
ABSTRACT
The role of the pyrimidine N(3)-H in binding of dUMP derivatives to thymidylate synthase was evaluated with the aid of a new dUMP analogue, 5-fluoro-4-thio-dUMP, synthesized by an improved thiation and enzymatic phosphorylation. The interaction of this analogue, and of 5-FdUMP, with the enzyme, and the pH-dependence of these interactions, were compared. Both were slow-binding competitive inhibitors of the enzyme from Ehrlich carcinoma, L1210 and CCRF-CEM cells, with Ki an order of magnitude higher for 5-fluoro-4-thio-dUMP than for 5-FdUMP. With both nucleotides, as well as the parent nucleosides, enzyme inactivation increased as the pH was lowered from 8 to 6. Maximum inactivation with 5-FdUrd was at pH 7.0, and with 5-fluoro-4-thio-dUrd at pH 6.0, in agreement with the higher pKa for the N(3)-H dissociation of the former, and pointing to participation of the N(3)-H as a hydrogen donor in binding to the enzyme.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Tionucleótidos
/
Timidilato Sintasa
/
Nucleótidos de Desoxiuracil
/
Fluorodesoxiuridilato
/
Proteínas de Neoplasias
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Biochem Biophys Res Commun
Año:
1987
Tipo del documento:
Article