Departamento de Química, Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, Ribeirão Preto, Avenida Bandeirantes 3900, Ribeirão Preto, SP 14040-901, Brazil.
J Membr Biol. 2011 Nov;244(1):9-20. doi: 10.1007/s00232-011-9391-5. Epub 2011 Oct 5.
We investigated the effect of the exogenous polyamines spermine, spermidine and putrescine on modulation by ATP, K⁺, Na⁺, NH₄⁺ and Mg²⁺ and on inhibition by ouabain of posterior gill microsomal Na⁺,K⁺-ATPase activity in the blue crab, Callinectes ornatus, acclimated to a dilute medium (21‰ salinity). This is the first kinetic demonstration of competition between spermine and spermidine for the cation sites of a crustacean Na⁺,K⁺-ATPase. Polyamine inhibition is enhanced at low cation concentrations: spermidine almost completely inhibited total ATPase activity, while spermine inhibition attained 58%; putrescine had a negligible effect on Na⁺,K⁺-ATPase activity. Spermine and spermidine affected both V and K for ATP hydrolysis but did not affect ouabain-insensitive ATPase activity. ATP hydrolysis in the absence of spermine and spermidine obeyed Michaelis-Menten behavior, in contrast to the cooperative kinetics seen for both polyamines. Modulation of V and K by K⁺, Na⁺, NH₄⁺ and Mg²⁺ varied considerably in the presence of spermine and spermidine. These findings suggest that polyamine inhibition of Na⁺,K⁺-ATPase activity may be of physiological relevance to crustaceans that occupy habitats of variable salinity.
我们研究了外源多胺精胺、亚精胺和腐胺对蓝蟹 Callinectes ornatus 后鳃微体 Na⁺，K⁺-ATP 酶活性的 ATP、K⁺、Na⁺、NH₄⁺和 Mg²⁺调节以及哇巴因抑制的影响，这些蟹适应于低盐环境（21‰盐度）。这是首次在甲壳动物 Na⁺，K⁺-ATP 酶中证明精胺和亚精胺对阳离子位点竞争的动力学证据。多胺抑制作用在低阳离子浓度下增强：亚精胺几乎完全抑制总 ATP 酶活性，而精胺抑制作用达到 58%；腐胺对 Na⁺，K⁺-ATP 酶活性几乎没有影响。精胺和亚精胺影响 ATP 水解的 V 和 K，但不影响哇巴因不敏感的 ATP 酶活性。在没有精胺和亚精胺的情况下，ATP 水解遵循米氏-门登动力学行为，而两种多胺则表现出协同动力学。K⁺、Na⁺、NH₄⁺和 Mg²⁺对 V 和 K 的调节在精胺和亚精胺存在时变化很大。这些发现表明，多胺抑制 Na⁺，K⁺-ATP 酶活性可能与适应可变盐度栖息地的甲壳类动物具有生理相关性。
