Ihara K, Abe T, Sugimura KI, Mukohata Y
J Exp Biol. 1992 Nov 1;172(Pt 1):475-485. doi: 10.1242/jeb.172.1.475.
The head piece separated from the A-ATP synthase of Halobacterium halobium hydrolyses ATP. This A1-ATPase is inhibited by nitrate but not by other chaotropic anions. The nitrate inhibition is noncompetitive with respect to ATP, reversible, and partially protected by chloride. In contrast, ATP synthase in situ (A1Ao-ATPase) is not inhibited by nitrate but apparently is inhibited by stronger chaotropic reagents, such as thiocyanate and trichloroacetate, which make the vesicle membrane permeable to protons. The mode of action of nitrate and chaotropic anions seems to differentiate A-ATPases from V-ATPases. Other strains of Halobacterium, Haloferax, Haloarcula, Halococcus and Natronobacterium, contain at least two polypeptides immunochemically similar to the two major subunits, (&agr;) (86x10(3 )Mr on SDS-PAGE) and &bgr; (64x10(3 )Mr), of the A-ATPase of Halobacterium halobium. When solubilized, membrane vesicles of these halobacteria hydrolyse ATP. Their ATPases are commonly sensitive to nitrate. They require high concentrations of the supporting salt but depend differently on chloride or sulfate/sulfite. The A-ATPases of Halobacteriaceae appear to diverge with respect to salt preference.
嗜盐菌（Halobacterium halobium）的A-ATP合酶头部片段可水解ATP。这种A1-ATP酶受硝酸盐抑制，但不受其他离液序列高的阴离子抑制。硝酸盐抑制作用对ATP而言是非竞争性的、可逆的，且部分受氯离子保护。相比之下，原位ATP合酶（A1Ao-ATP酶）不受硝酸盐抑制，但显然受更强的离液序列高的试剂抑制，如硫氰酸盐和三氯乙酸，这些试剂可使囊泡膜对质子具有通透性。硝酸盐和离液序列高的阴离子的作用方式似乎使A-ATP酶与V-ATP酶有所不同。嗜盐菌属、嗜盐栖热菌属、嗜盐碱杆菌属、盐球菌属和嗜盐碱芽孢杆菌属的其他菌株至少含有两种与嗜盐菌A-ATP酶的两个主要亚基（α（SDS-PAGE上Mr为86×10³）和β（Mr为64×10³））免疫化学相似的多肽。当这些嗜盐菌的膜囊泡溶解后可水解ATP。它们的ATP酶通常对硝酸盐敏感。它们需要高浓度的支持盐，但对氯离子或硫酸盐/亚硫酸盐的依赖性不同。盐杆菌科的A-ATP酶在盐偏好方面似乎存在差异。
