5--Iodo--5'--amino--2',5'--dideoxyuridine--5'--N'--triphosphate: synthesis, chemical properties, and effect on Escherichia coli thymidine kinase activity

Journal Article · Thu Jan 01 04:00:00 EST 1976 · J. Biol. Chem.; (United States)

OSTI ID:6434260

Chen, M S; Ward, D C; Prusoff, W H

5-Iodo-5'-amino-2',5'-dideoxyuridine-5'-N'-triphosphate (AIdUTP), a phosphoramidate analog of 5-iodo-2',5'-dideoxyuridine 5'-triphosphate (IdUTP), was synthesized and some of its chemical and biological properties were investigated. Although AIdUTP is stable in alkaline solutions, below pH 8 it undergoes degradation by a novel phosphorylysis reaction which exhibits first order kinetics. Inclusion of magnesium ion in the reaction mixture decreased the rate of degradation. Protonation of a group on AIdUTP which has a pK/sub ..cap alpha../ of 6.10, presumably the secondary ionized oxygen on the ..gamma.. phosphate, precedes phosphorylysis. The only detectable reaction products are the nucleoside, 5-iodo-5'-amino-2',5'-dideoxyuridine (AIdUrd), and trimetaphosphate. A mechanism for the acid catalyzed phosphorylysis of AIdUTP is proposed. AIdUTP, like TTP, converts Escherichia coli thymidine kinase into an inactive dimer with a sedimentation coefficient of 5.78 S. AIdUTP is, however, 60-fold more potent as an allosteric inhibitor than is TTP at pH 7.8. Although the inhibitory effect of TTP is markedly reduced at high pH, the activity of AIdUTP is lowered only slightly. The allosteric effects of AIdUTP also differ from those of IdUTP, which is an inhibitor at low pH but a strong activator above pH 7.4. 5-Iodo-2'-deoxycytidine 5'-triphosphate, a potent enzyme activator, cannot completely reverse the AIdUTP inhibition, even when present at a 150-fold molar excess.

• Research Organization: Yale Univ. School of Medicine, New Haven, CT
• OSTI ID: 6434260
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 251:16; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ANTIMETABOLITES
ANTIMITOTIC DRUGS
ATOMIC IONS
AZINES
BACTERIA
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
CHARGED PARTICLES
CHEMICAL PROPERTIES
DRUGS
ENZYMES
ESCHERICHIA COLI
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IODODEOXYURIDINE
IODOURACILS
IONS
KINETICS
MAGNESIUM IONS
METABOLISM
MICROORGANISMS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHOTRANSFERASES
PYRIMIDINES
REACTION KINETICS
RIBOSIDES
SYNTHESIS
TRANSFERASES
URACILS