嗜热栖热菌属X-1菌株苏氨酸脱氨酶的纯化及性质
Purification and properties of threonine deaminase from the X-1 isolate of the genus Thermus.
作者信息
Higa E H, Ramaley R F
出版信息
J Bacteriol. 1973 May;114(2):556-62. doi: 10.1128/jb.114.2.556-562.1973.
Threonine deaminase (l-threonine dehydratase EC 4.2.1.16) has been partially purified from a new extreme thermophilic bacterium, Thermus X-1, which is similar to T. aquaticus YT-1. The threonine deaminase of strain X-1 has a maximal rate of reaction at 85 to 90 C and is more thermostable than the threonine deaminase from mesophilic bacteria. The enzyme has an apparent molecular weight of 100,000 to 115,000, a K(m) for l-threonine of 14 mM, a pH optimum of 8.0, and like other threonine deaminases also catalyzes the deamination of serine. However the Thermus X-1 threonine deaminase does not show a strong feedback inhibition by isoleucine. It is suggested that the regulation of the biosynthesis of isoleucine in this extreme theromophile may resemble that reported in Rodospirillum rubrum.
苏氨酸脱氨酶（L-苏氨酸脱水酶，EC 4.2.1.16）已从一种新的嗜热细菌嗜热栖热菌X-1（与嗜热水生栖热菌YT-1相似）中部分纯化出来。X-1菌株的苏氨酸脱氨酶在85至90℃时反应速率最高，并且比嗜温细菌的苏氨酸脱氨酶更耐热。该酶的表观分子量为100,000至115,000，L-苏氨酸的K(m)为14 mM，最适pH为8.0，并且与其他苏氨酸脱氨酶一样，也催化丝氨酸的脱氨反应。然而，嗜热栖热菌X-1的苏氨酸脱氨酶对异亮氨酸没有强烈的反馈抑制作用。有人提出，这种嗜热菌中异亮氨酸生物合成的调节可能类似于在深红红螺菌中报道的情况。
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