Harris C L
J Bacteriol. 1981 Feb;145(2):1031-5. doi: 10.1128/jb.145.2.1031-1035.1981.
Cysteine has been shown to inhibit growth in Escherichia coli strains C6 and HfrH 72, but not M108A. Growth inhibition was overcome by inclusion of isoleucine, leucine, and valine in the medium. Isoleucine biosynthesis was apparently affected, since addition of this amino acid alone could alter the inhibitory effects of cysteine. Homocysteine, mercaptoethylamine, and mercaptoethanol inhibited growth to varying degrees in some strains, these effects also being prevented by addition of branched-chain amino acids. Cysteine, mercaptoethylamine, and homocysteine were inhibitors of threonine deaminase but not transaminase B, two enzymes of the ilvEDA operon. Cysteine inhibition of threonine deaminase was reversed by threonine, although the pattern of inhibition was mixed. These results suggest a relationship between the growth-inhibitory effects of cysteine and other sulfur compounds and the inhibition of isoleucine synthesis at the level of threonine deaminase.
已证明半胱氨酸可抑制大肠杆菌菌株C6和HfrH 72的生长，但对M108A菌株无抑制作用。在培养基中添加异亮氨酸、亮氨酸和缬氨酸可克服生长抑制。异亮氨酸的生物合成显然受到影响，因为单独添加这种氨基酸可改变半胱氨酸的抑制作用。同型半胱氨酸、巯基乙胺和巯基乙醇在某些菌株中不同程度地抑制生长，添加支链氨基酸也可防止这些作用。半胱氨酸、巯基乙胺和同型半胱氨酸是苏氨酸脱氨酶的抑制剂，但不是ilvEDA操纵子的两种酶——转氨酶B的抑制剂。苏氨酸可逆转半胱氨酸对苏氨酸脱氨酶的抑制作用，尽管抑制模式是混合的。这些结果表明，半胱氨酸和其他硫化合物的生长抑制作用与苏氨酸脱氨酶水平上异亮氨酸合成的抑制之间存在关联。
