皮状丝孢酵母同步利用葡萄糖/木糖的糖转运动力学简

皮状丝孢酵母（ Trichosporon cutaneum）能够同步利用葡萄糖和木糖生产油脂。以2脱氧葡萄糖（2 DOG）为底物，考察皮状丝孢酵母糖跨膜运输的转运动力学。结果表明：2 DOG转运符合米氏方程，表观米氏常数Km为0.19 mmol/L，最大转运速率Vmax为14.1 nmol/（ min＆#183;mg）。葡萄糖和木糖均竞争性抑制2 DOG转运，葡萄糖表观抑制常数Ki远低于木糖，表明存在一个共用转运体系，且该转运体系对葡萄糖亲和力更高。大量木糖与2 DOG同时转运到胞内，进一步说明木糖与葡萄糖共运输。代谢抑制剂和pH对糖转运有明显影响，说明质子/底物同向运输系统是该酵母的主要糖转运系统。

Kinetics of sugar transport by Trichosporon cutaneum using simultaneous utilization of glucose and xylose

The yeast Trichosporon cutaneum can utilize glucose and xylose simultaneously for microbial lipid production. The sugar transport kinetics was studied by using 2-deoxyglucose （ 2-DOG ） as a surrogate substrate.It was found that kinetics data of 2-DOG transport fitted well to Michaelis-Menten plot and that the apparent Km of 0.19 mmol/L and Vmax of 14.1 nmol/（ min＆#183;mg） were obtained.Both glucose and xylose inhibited competitively the transport of 2-DOG, indicating that these compounds shared the same transporter.The apparent inhibition constant Ki of glucose was much lower than that of xylose, suggesting a higher affinity of the transporter to glucose than xylose.The fact that large amount of xylose was uptaken together with 2-DOG further supported the co-transport of glucose and xylose.As 2-DOG transport was sensitive to metabolic inhibitors and pH,an H＋/sugar-symport system was suggested as the main sugar transporter.