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http://repositorio.pediatria.gob.mx:8180/handle/20.500.12103/2749| Título : | Pyruvate kinase revisited. the activating effect of k+ |
| Creador: | Oria Hernández Jesús |
| Nivel de acceso: | Open access |
| Palabras clave : | Escherichia coli - Enzymology Potassium - pharmacology Piruvato Quinasa - Metabolism Escherichia coli - Enzymology Potassium - Pharmacology Pyruvate Kinase - Metabolism |
| Descripción : | For more than 50 years, it has been known that K(+) is an essential activator of pyruvate kinase (Kachmar, J. F., and Boyer, P. D. (1953) J. Biol. Chem. 200, 669-683). However, the role of K(+) in the catalysis by pyruvate kinase has not been totally understood. Previous studies without K(+) showed that the affinity of ADP-Mg(2+) depends on the concentration of phosphoenolpyruvate, although the kinetics of the enzyme at saturating K(+) concentrations show independence in the binding of substrates (Reynard, A. M., Hass, L. F., Jacobsen, D. D. & Boyer, P. D. (1961) J. Biol. Chem. 236, 2277-2283). Here, we explored the kinetics of the enzyme with and without K(+). The results show that without K(+), the kinetic mechanism of pyruvate kinase changes from random to ordered with phosphoenol-pyruvate as first substrate. V(max) with K(+) was about 400 higher than without K(+). In the presence of K(+), the affinities for phosphoenol-pyruvate, ADP-Mg(2+), oxalate, and ADP-Cr(2+) were 2-6-fold higher than in the absence of K(+). This as well as fluorescence data also indicate that K(+) is involved in the acquisition of the active conformation of the enzyme, allowing either phosphoenolpyruvate or ADP to bind independently (random mechanism). In the absence of K(+), ADP cannot bind to the enzyme until phosphoenolpyruvate forms a competent active site (ordered mechanism). We propose that K(+) induces the closure of the active site and the arrangement of the residues involved in the binding of the nucleotide |
| Colaborador(es) u otros Autores: | Cabrera Nallely Pérez Montfort Ruy Ramírez Silva Leticia |
| Fecha de publicación : | 2005 |
| Tipo de publicación: | Artículo |
| Formato: | |
| Identificador del Recurso : | 10.1074/jbc.M508490200 |
| Fuente: | J Biol Chem 280(45):37924-37929 |
| URI : | http://repositorio.pediatria.gob.mx:8180/handle/20.500.12103/2749 |
| Idioma: | eng |
| Aparece en las colecciones: | Artículos |
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