Hill coefficient ratios give binding ratios of allosteric enzyme effectors; inhibition, activation, and squatting in deoxycytidylate aminohydrolase (EC 3.5.4.12)
Arch Biochem Biophys
; 289(1): 12-8, 1991 Aug 15.
Article
em En
| MEDLINE
| ID: mdl-1898058
ABSTRACT
The ratio of the steady-state kinetic Hill coefficients of two different effectors equals (under some rather weak general assumptions) the ratio in which the effectors displace each other from an enzyme. This principle can make implications of experimental allosteric enzyme kinetic data immediately apparent. We can use it to find that one molecule of the allosteric inhibitor of dCMP aminohydrolase, at moderately high effector concentrations, displaces one molecule of substrate, or one molecule of activator, whereas at very high concentrations, one molecule of inhibitor displaces two of substrate. Further use of the principle suggests that substrate, at high concentrations, binds binds to activator sites. However, ratios of substrate, activator, and inhibitor Hill coefficients are incompatible with a simple model of activation in which substrate and activator are bound to the same conformation.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
DCMP Desaminase
Limite:
Animals
Idioma:
En
Revista:
Arch Biochem Biophys
Ano de publicação:
1991
Tipo de documento:
Article