Fontan E, Truffa-Bachi P
J Biol Chem. 1978 Apr 25;253(8):2754-7.
The inactivation of the aspartokinase I-homoserine dehydrogenase I by iodoacetic acid and the effect on the sensitivity to its inhibitor, L-threonine, were examined. Both aspartokinase and homoserine dehydrogenase inactivation, as well as the dehydrogenase desensitization toward L-threonine occur as a pseudo-first order process. During its inactivation, the aspartokinase remains sensitive to L-threonine. At 50% inactivation, the inhibition curve of the aspartokinase by L-threonine displays homotropic cooperative effects. This alkylated protein retains eight binding sites for L-threonine. During the carboxymethylation, the protein remains in the tetrameric form until half of the kinase activity is lost. At the end of the inactivation aggregate forms and dimers appear.
研究了碘乙酸对天冬氨酸激酶I-高丝氨酸脱氢酶I的失活作用及其对其抑制剂L-苏氨酸敏感性的影响。天冬氨酸激酶和高丝氨酸脱氢酶的失活以及脱氢酶对L-苏氨酸的脱敏作用均呈现假一级反应过程。在失活过程中，天冬氨酸激酶对L-苏氨酸仍保持敏感。在50%失活时，L-苏氨酸对天冬氨酸激酶的抑制曲线显示出同促协同效应。这种烷基化蛋白保留了8个L-苏氨酸结合位点。在羧甲基化过程中，该蛋白在激酶活性丧失一半之前一直保持四聚体形式。失活结束时形成聚集体并出现二聚体。
