THREONINE (SERINE) DEHYDRATASE FROM CUSCUTA-CAMPESTRIS YUNCK
THREONINE (SERINE) DEHYDRATASE FROM CUSCUTA-CAMPESTRIS YUNCK
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DOI：
10.1016/s0015-3796(83)80068-7
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
NATH, M
中科院分区：
文献类型：
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作者：
MADAN, VK;NATH, M
L-苏氨酸脱氢酶经纯化70倍，回收率为35%。油菜通过3种凝胶浓度（5%、7.5%和10%）下pH 7.0、7.5和9.5的聚丙烯酰胺凝胶电泳判断，该酶明显同质。凝胶过滤分析显示纯化酶的MW为230，000。十二烷基硫酸钠存在下的凝胶电泳表明存在4个亚基/酶分子。该酶每摩尔蛋白质含有4个巯基。该酶的最适pH为8.5。该酶不被异亮氨酸抑制，并且不需要外部添加磷酸吡哆醛以获得其最大活性。该酶对AMP、ADP、β-ATP不敏感。巯基乙醇和谷胱甘肽。碘乙酸盐、PCMB [对-苯甲酸汞]和乙基马来酰亚胺在1 × 10 - 4时分别抑制酶12%、88%和70%。10-2 M.甘氨酸、精氨酸和组氨酸对该酶有轻微的激活作用。
L-threonine dehydratase was purified 70-fold, with 35% recovery from the seeds of C. campestris. The enzyme was apparently homogeneous as judged by polyacrylamide gel electrophoresis at pH 7.0, 7.5 and 9.5 at 3 concentrations of gels (5, 7.5 and 10%). Gel filtration analysis revealed a MW of 230,000 for the purified enzyme. Gel electrophoresis in the presence of sodium dodecyl sulfate indicated the presence of 4 subunits/enzyme molecule. The enzyme contains 4 sulfhydryl groups/mol of protein. The biodegradative L-threonine dehydratase activity showed optimum at pH 8.5. The enzyme was not inhibited by isoleucine and does not require externally added pyridoxal phosphate for its maximum activity. The enzyme was insensitive to AMP, ADP, .beta.-mercaptoethanol and glutathione. Iodoacetate, PCMB [para-mercuribenzoate] and ethylmaleimide inhibited the enzyme 12, 88 and 70%, respectively, at 1 .times. 10-2 M. The enzyme was slightly activated by glycine, arginine and histidine.