Por favor, use este identificador para citar o enlazar este ítem:
http://repositorio.pediatria.gob.mx:8180/handle/20.500.12103/2795| Título : | Selectivity of pyruvate kinase for Na+ and K+ in water/dimethylsulfoxide mixtures |
| Creador: | Ramírez Silva L |
| Nivel de acceso: | Open access |
| Palabras clave : | Dimetilsulfóxido - química potasio - metabolismo Piruvato Quinasa - química Sodio - metabolismo Agua - química Dimethyl Sulfoxide - chemistry Potassium - metabolism Pyruvate Kinase - chemistry Sodium - metabolism Water - chemistry dimetilsulfóxido ion de magnesio ion de potasio piruvato quinasa ion de sodio dimethylsulfoxide magnesium ion potassium ion pyruvate kinase sodium ion |
| Descripción : | In aqueous media, muscle pyruvate kinase is highly selective for K+ over Na+. We now studied the selectivity of pyruvate kinase in water/dimethylsulfoxide mixtures by measuring the activation and inhibition constants of K+ and Na+, i.e. their binding to the monovalent and divalent cation binding sites of pyruvate kinase, respectively [Melchoir J.B. (1965) Biochemistry 4, 1518-1525]. In 40% dimethylsulfoxide the K0.5 app for K+ and Na+ were 190 and 64-fold lower than in water. Ki app for K+ and Na+ decreased 116 and 135-fold between 20 and 40% dimethylsulfoxide. The ratios of Ki app/K0.5 app for K+ and Na+ were 34-3.5 and 3.3-0.2, respectively. Therefore, dimethylsulfoxide favored the partition of K+ and Na+ into the monovalent and divalent cation binding sites of the enzyme. The kinetics of the enzyme at subsaturating concentrations of activators show that K+ and Mg2+ exhibit high selectivity for their respective cation binding sites, whereas when Na+ substitutes K+, Na+ and Mg2+ bind with high affinity to their incorrect sites. This is evident by the ratio of the affinities of Mg2+ and K+ for the monovalent cation binding site, which is close to 200. For Na+ and Mg2+ this ratio is approximately 20. Therefore, the data suggest that K+ induces conformational changes that prevent the binding of Mg2+ to the monovalent cation binding site. Circular dichroism spectra of the enzyme and the magnitude of the transfer and apparent binding energies of K+ and Na+ indicate that structural arrangements of the enzyme induced by dimethylsulfoxide determine the affinities of pyruvate kinase for K+ and Na+ |
| Colaborador(es) u otros Autores: | Oria Hernández J |
| Fecha de publicación : | 2003 |
| Tipo de publicación: | Artículo |
| Formato: | |
| Identificador del Recurso : | 10.1046/j.1432-1033.2003.03605.x |
| Fuente: | Eur J Biochem 270(11):2377-2385 |
| URI : | http://repositorio.pediatria.gob.mx:8180/handle/20.500.12103/2795 |
| Idioma: | spa |
| Aparece en las colecciones: | Artículos |
Ficheros en este ítem:
No hay ficheros asociados a este ítem.
Los ítems de DSpace están protegidos por copyright, con todos los derechos reservados, a menos que se indique lo contrario.