| Texto completo | |
| Autor(es): |
Moraes, Cintya M.
;
Lucena, Malson N.
;
Garcon, Daniela P.
;
Pinto, Marcelo R.
;
Fabri, Leonardo M.
;
Faleiros, Rogerio O.
;
Fontes, Carlos F. L.
;
McNamar, John C.
;
Leone, Francisco A.
Número total de Autores: 9
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Membrane Biology; v. 253, n. 3, p. 17-pg., 2020-05-22. |
| Resumo | |
We provide a kinetic characterization of (Na+, K+)-ATPase activity in a posterior gill microsomal fraction from the grapsid crab Goniopsis cruentata. (Na+, K+)-ATPase activity constitutes 95% of total ATPase activity, and sucrose density centrifugation reveals an ATPase activity peak between 25 and 35% sucrose, distributed into two, partially separated protein fractions. The (Na+, K+)-ATPase alpha-subunit is localized throughout the ionocyte cytoplasm and has an M-r of approximate to 10 kDa and hydrolyzes ATP obeying cooperative kinetics. Low (V-M = 186.0 +/- 9.3 nmol Pi min(-1) mg(-1) protein and K-0.5 = 0.085 +/- 0.004 mmol L-1) and high (V-M = 153.4 +/- 7.7 nmol Pi min(-1) mg(-1) protein and K-0.5 = 0.013 +/- 0.0006 mmol L-1) affinity ATP binding sites were characterized. At low ATP concentrations, excess Mg2+ stimulates the enzyme, triggering exposure of a high-affinity binding site that accounts for 50% of (Na+, K+)-ATPase activity. Stimulation by Mg2+ (V-M = 425.9 +/- 25.5 nmol Pi min(-1) mg(-1) protein, K-0.5 = 0.16 +/- 0.01 mmol L-1), K+ (V-M = 485.3 +/- 24.3 nmol Pi min(-1) mg(-1) protein, K-0.5 = 0.9 +/- 0.05 mmol L-1), Na+ (V-M = 425.0 +/- 23.4 nmol Pi min(-1) mg(-1) protein, K-0.5 = 5.1 +/- 0.3 mmol L-1) and NH4+ (V-M = 497.9 +/- 24.9 nmol Pi min(-1) mg(-1) protein, K-0.5 = 9.7 +/- 0.5 mmol L-1) obeys cooperative kinetics. Ouabain inhibits up to 95% of ATPase activity with K-I = 196.6 +/- 9.8 mu mol L-1. This first kinetic characterization of the gill (Na+, K+)-ATPase in Goniopsis cruentata enables better comprehension of the biochemical underpinnings of osmoregulatory ability in this semi-terrestrial mangrove crab. [GRAPHICS] . (AU) | |
| Processo FAPESP: | 16/25336-0 - Estudo bioquímico comparativo da (Na+, K+)-ATPase branquial de Macrobrachium amazonicum (Heller, 1862) habitantes de regiões costeiras e continentais |
| Beneficiário: | Francisco de Assis Leone |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 13/24252-9 - O papel da (Na+,K+)-ATPase na capacidade osmorregulatória do caranguejo Ucides cordatus: uma abordagem bioquímica e molecular |
| Beneficiário: | Malson Neilson de Lucena |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |