Na(+), K(+)-ATPase activity in gill microsomes from the blue crab, Callinectes danae, acclimated to low salinity: Novel perspectives on ammonia excretion
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
19/10/2012
19/10/2012
2009
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Resumo |
This investigation provides an extensive characterization of the modulation by ATP, Mg(2+), Na(+), K(+) and NH(4)(+) of a gill microsomal (Na(+),K(+))-ATPase from Callinectes danae acclimated to 15 parts per thousand salinity. Novel findings are the lack of high-affinity ATP-binding sites and a 10-fold increase in enzyme affinity for K(+) modulated by NH4+, discussed regarding NH4+ excretion in benthic marine crabs. The (Na(+),K(+))-ATPase hydrolyzed ATP at a maximum rate of 298.7 +/- 16.7 nmol Pi min(-1) mg(-1) and K(0.5) = 174.2 +/- 9.8 mmol L(-1) obeying cooperative kinetics (n(H) = 1.2). Stimulation by sodium (V = 308.9 +/- 15.7 nmol Pi min(-1) mg(-1), K(0.5) = 7.8 +/- 0.4 mmol L(-1)), magnesium (299.2 +/- 14.1 nmol Pi min(-1) mg(-1), K(0.5) = 767.3 +/- 36.1 mmol L(-1)), potassium (300.6 +/- 153 nmol Pi min(-1) mg(-1), K(0.5) = 1.6 +/- 0.08 mmol L(-1)) and ammonium (V = 345.1 +/- 19.0 nmol Pi min(-1) mg(-1), K(0.5) = 6.0 +/- 0.3 mmol L(-1)) ions showed site-site interactions. Ouabain inhibited (Na(+),K(+))-ATPase activity with K(1) = 45.1 +/- 2.5 mu mol L(-1), although affinity for the inhibitor increased (K(1) = 22.7 +/- 1.1 mu mol L(-1)) in 50 mmol L(-1) NH(4)(+). Inhibition assays using ouabain plus oligomycin or ethacrynic acid suggest mitochondrial F(0)F(1)- and K(+)-ATPase activities, respectively. Ammonium and potassium ions synergistically stimulated specific activity up to 72%, inferring that these ions bind to different sites on the enzyme molecule, each modulating stimulation by the other. (C) 2009 Elsevier Inc. All rights reserved. Funda Ao de Amparo a Pesquisa do Estado cle S o Paulo (FAPESP) Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) |
Identificador |
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY, v.153, n.2, p.141-148, 2009 1095-6433 http://producao.usp.br/handle/BDPI/20874 10.1016/j.cbpa.2009.01.020 |
Idioma(s) |
eng |
Publicador |
ELSEVIER SCIENCE INC |
Relação |
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology |
Direitos |
restrictedAccess Copyright ELSEVIER SCIENCE INC |
Palavras-Chave | #Acclimation #Ammonium excretion #Callinectes danae #Euryhaline crab #(Na(+),K(+))-ATPase #Potassium ion #SHRIMP MACROBRACHIUM-OLFERSII #ALPHA-SUBUNIT EXPRESSION #SHORE CRAB #CARCINUS-MAENAS #ION-TRANSPORT #PHOSPHATASE ACTIVITY #CHASMAGNATHUS-GRANULATA #NA,K-ATPASE ISOZYMES #NITROGEN-EXCRETION #DEPENDENT ATPASE #Biochemistry & Molecular Biology #Physiology #Zoology |
Tipo |
article original article publishedVersion |