Hu Chun-Keng, Bai Feng-Wu, An Li-Jia
Department of Bioengineering, Huaqiao University, Quanzhou 362011, China.
Sheng Wu Gong Cheng Xue Bao. 2004 Sep;20(5):784-9.
Although alterations in fatty acid composition of phospholipids in plasma membranes had no effect on activities of plasma membrane ATPases of a self-flocculating fusant of Schizosaccharomyces pombe and Saccharomyces cerevisiae cells grown in the absence of ethanol (basal enzymes), they significantly affected the susceptibilities of the enzymes to in vivo activation induced by ethanol: the maximal values for the activated enzymes in cells pregrown with 0.6 mmol/L palmitic, linoleic or linolenic acid respectively were 3.6, 1.5 and 1.2-fold higher than their respective basal levels (in cells grown without ethanol), whereas the corresponding value for cells pregrown in the absence of fatty acid was 2.3-fold, with the concentrations of ethanol for the above maximal in vivo activation of enzymes being 7%, 6%, 6% and 7% (V/V) respectively. The Km values for ATP, the pH profiles, and the sensitivities to orthovanadate of the basal and the activated plasma membrane ATPases were essentially identical; however, the v(max) values of activated enzymes increased significantly. It was found that the characteristics of phospholipid fatty acid composition of plasma membrane leading to the enhanced ethanol tolerance of this strain, were also efficacious to increase the percentage of activation of plasma membrane ATPase per unit of ethanol. These data support a close correlation between the ethanol tolerance of this strain and the sensitivity of its plasma membrane ATPase to the in vivo ethanol-induced activation.
虽然在无乙醇条件下生长的粟酒裂殖酵母和酿酒酵母的自絮凝融合体细胞的质膜中磷脂脂肪酸组成的改变对质膜ATP酶的活性没有影响（基础酶），但它们显著影响了这些酶对乙醇体内激活的敏感性：分别用0.6 mmol/L棕榈酸、亚油酸或亚麻酸预培养的细胞中，激活酶的最大值分别比各自的基础水平（无乙醇培养的细胞）高3.6倍、1.5倍和1.2倍，而在无脂肪酸条件下预培养的细胞的相应值为2.3倍，上述酶体内最大激活浓度的乙醇浓度分别为7%、6%、6%和7%（V/V）。基础和激活的质膜ATP酶对ATP的Km值、pH曲线以及对原钒酸盐的敏感性基本相同；然而，激活酶的v(max)值显著增加。研究发现，导致该菌株乙醇耐受性增强的质膜磷脂脂肪酸组成特征，对于提高每单位乙醇的质膜ATP酶激活百分比也有效。这些数据支持了该菌株的乙醇耐受性与其质膜ATP酶对体内乙醇诱导激活的敏感性之间的密切相关性。
