Biochemical Studies on Acetic Acid Bacteria

细胞色素A1是一种经典的细胞色素，早在20世纪30年代就已经在醋酸菌中被检测到，50年代被鉴定为一种末端氧化酶。然而，最近的研究并没有证实之前的观察结果。我们在乙酸乙酸杆菌中发现了一个类似细胞色素al的发色团，本研究对其进行了纯化和鉴定。用辛基葡萄糖苷从菌膜上增溶细胞色素，并用单柱层析纯化。纯化的细胞色素在600-610 nm附近有一个宽阔的α峰，在氰化物存在下，在589 nm处有一个尖锐的峰。细胞色素的一氧化碳差示光谱表明，细胞色素中存在甲型细胞色素。细胞色素含有L摩尔，每一种血红素b和可能一种铜试剂。这些结果表明，从A.Aceti就是所谓的细胞色素al，因而经典的细胞色素的存在得到了再次证实。该酶由55 kDa、35 kDa、22 kDa和18 kDa四种多肽组成，其天然沉淀值为6.3s。该酶具有很高的泛喹酚氧化酶活性(每毫克蛋白质每分钟氧化140-160微摩尔的泛喹酚)。当重组为蛋白质脂质体时，细胞色素可以在泛喹酚的氧化过程中产生电化学质子梯度。因此，黄曲霉的细胞色素al。Aceti已被证明是一种细胞色素BA末端氧化酶，能够在泛喹酚氧化的过程中产生电化学质子梯度。

Cytochrome al is a classic cytochrome that in the 1930s had already been detected in Acetobacter strains and in the 1950s was identified as a terminal oxidase. However, recent studies did not substantiate the previous observations. We have detected a cytochrome al like chromophore in Acetobacter aceti, which was purified and charactarized in this study. The cytochrome was solubilized from membranes of the strain with octyl glucoside and was purified by single column chromatography. The purified cytochrome exhibited a broad alpha peak around 600-610 nm, which turned to a sharp peak at 589 nm in the presence of cyanide. Carbon monoxide difference spectra of the cytochrome indicated the presence of an alphatipe cytochrome. The cytochrome contained l mol each of hemes b and probably one copperion. These results suggest that the cytochrome purified from A。 aceti is the so-called cytochrome al, and thus the existence of the classic cytochrome has been reconfirmed. The purified enzyme consisted of four polypeptides of 55, 35, 22 and 18 kDa, and it showed a sedimentation coefficient of 6.3s in the native form. The enzyme had a high ubiquinol oxidase activity (140-160 micromoles of ubiquinol oxidized per min per mg of protein). When reconstituted into proteoliposomes, the cytochrome could generate an electrochemical proton gradient during oxidation of ubiquinol. Thus, cytochrome al of A。 aceti has been shown to be a cytochrome ba terminal oxidase capable of generating an electrochemical proton gradient concomitant with ubiquinol oxidation.