莽草酸途径
生物化学
甲戊酸途径
生物合成
酿酒酵母
预酸化
羟基苯甲酸盐
芳香族氨基酸
酵母
脱羧
大肠杆菌
酪氨酸
生物
化学
立体化学
氨基酸
酶
催化作用
基因
出处
期刊:Fems Microbiology Letters
[Oxford University Press]
日期:2001-09-01
卷期号:203 (2): 131-139
被引量:255
标识
DOI:10.1111/j.1574-6968.2001.tb10831.x
摘要
The quinoid nucleus of the benzoquinone, ubiquinone (coenzyme Q; Q), is derived from the shikimate pathway in bacteria and eukaryotic microorganisms. Ubiquinone is not considered a vitamin since mammals synthesize it from the essential amino acid tyrosine. Escherichia coli and other Gram-negative bacteria derive the 4-hydroxybenzoate required for the biosynthesis of Q directly from chorismate. The yeast, Saccharomyces cerevisiae, can either form 4-hydroxybenzoate from chorismate or tyrosine. However, unlike mammals, S. cerevisiae synthesizes tyrosine in vivo by the shikimate pathway. While the reactions of the pathway leading from 4-hydroxybenzoate to Q are the same in both organisms the order in which they occur differs. The 4-hydroxybenzoate undergoes a prenylation, a decarboxylation and three hydroxylations alternating with three methylation reactions, resulting in the formation of Q. The methyl groups for the methylation reactions are derived from S-adenosylmethionine. While the prenyl side chain is formed by the 2-C-methyl-D-erythritol 4-phosphate (non-mevalonate) pathway in E. coli, it is formed by the mevalonate pathway in the yeast.
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