热带假丝酵母多倍体变种的细胞色素P450和尿素在烷烃代谢中的作用

建立了可行的细胞色素 P450测定方法。考察了以烷烃为单一碳源的酵母细胞色素P450的一氧化碳差示光谱,峰值约为455nm。观察了烷烃培养的酵母细胞色素 P450在生长期中的消长。比较了十四醇、十四醇添加苯巴比妥、以及正十四烷等三种不同培养条件下酵母细胞色素P450的含量和发酵产物的成份。结果表明,细胞色素 P450为烷烃转化成二元酸所必需。烷烃为单一碳源培养酵母时,培养基中过量尿素(0.2%以上)促进烷烃利用和酵母生长,降低细胞色素 P450生成和二元酸的积累。根据上述实验结果和本研究室以前报道,提出了烷烃代谢调控模式。

INVOLVEMENT OF CYTOCHROME P450 AND UREA IN THE ALKANE METABOLISM BY CANDIDA TROPICALIS

A method for determining cytochrome P450 was established.Carbon monoxide-difference spectrum of cytochrome P450 was examined in the yeast grown on al- kane as the sole carbon source,and a peak at about 455 nm was observed.Evolution of cyto- chrome P450 during the growth cycle of Candida tropicalis on n-pentadecane was studied. The amount of cytochrome P450 and the fermentation products were compared in the yeast grown on tetradecanol,tetradecanol plus phenobarbitol,or n-tetradecane.The results indicated that cytochrome P450-containing hydroxylase system was responsible not only for the initial oxidation of alkane,but also for the ω-oxidation of fatty acid in forming dicarbo- xylic acid. When the yeast was grown on alkane,the presence of an excess urea(above 0.2%)re- duced both the amount of cytochrome P450 and long-chain dicarboxylic acid greatly and in- fluenced the alkane utilization slightly,but rather enhanced the growth of the yeast appreci- ably. Based on the above experimental results and other published work of our laboratory, the regulation of alkane metabolism is incorporated into a scheme.