Komnick H, Schmitz M, Hinssen H
Eur J Cell Biol. 1980 Feb;20(3):217-27.
Hydrogencarbonate and chloride activated, ouabain-insensitive ATPase activities are demonstrated in the salt-absorbing rectum of larval dragonflies. Maximal activation is achieved at approx. 30 mM HCO3- and 20 mM Cl-, respectively. The stimulation of each anion obeys Michaelis-Menten kinetics Km values are 4.65 mM for HCO3-- and 10.25 mM for Cl--activation. The activating anion of one type of ATPase simultaneously exerts an inhibitory effect on the other. Cl--activation is also reduced by Mg.ATP in concentrations above 0.5 mM and by Tris-Hepes buffer exceeding 2.5 mM. Both anion-dependent ATPase activities are found enriched in subcellular membraneous fractions of the rectum. Thiocyanate inhibits both activities and causes a significant decrease in rectal uptake of radioactive chloride from hypo-osmotic external solution. In the case of HCO3- dependent ATPase a competitive inhibition as SCN- was found with an inhibitor constant of Ki=0.5 mM.
在幼虫蜻蜓的吸盐直肠中证实了碳酸氢盐和氯离子激活的、哇巴因不敏感的ATP酶活性。分别在约30 mM HCO₃⁻和20 mM Cl⁻时达到最大激活。每种阴离子的刺激均符合米氏动力学，HCO₃⁻激活的Km值为4.65 mM，Cl⁻激活的Km值为10.25 mM。一种类型的ATP酶的激活阴离子同时对另一种ATP酶产生抑制作用。浓度高于0.5 mM的Mg·ATP和超过2.5 mM的Tris-Hepes缓冲液也会降低Cl⁻激活。两种阴离子依赖性ATP酶活性均在直肠的亚细胞膜部分中富集。硫氰酸盐抑制这两种活性，并导致直肠从低渗外部溶液中摄取放射性氯离子的量显著减少。对于HCO₃⁻依赖性ATP酶，发现SCN⁻具有竞争性抑制作用，抑制常数Ki = 0.5 mM。
