Abstract A stable activity which transfers the amino group from glutamate to prephenate was extracted from 4-day old etiolated shoots of sorghum. The activity was retained on DEAE cellulose and eluted as a single peak. Prephenate aminotransferase co-eluted with a very abundant α-ketoglutarate: aspartate aminotransferase, but heating at 70 °C resulted in loss of α-ketoglutarate: aspartate activity with
摘要 从 4 天龄的高粱黄化枝条中提取了一种稳定的活性,可将
氨基从谷
氨酸盐转移到预苯酸盐。该活性保留在
DEAE
纤维素上并作为单峰洗脱。Prephenate
氨基转移酶与非常丰富的 α-酮
戊二酸:
天冬氨酸氨基转移酶共洗脱,但在 70 °C 加热导致 α-酮
戊二酸:
天冬氨酸活性丧失,而 prephenate:谷
氨酸
氨基转移酶活性几乎完全保留。加热后的酶对 prephenate 显示出高亲和力和特异性。在测试的 7 个供体中,只有谷
氨酸和
天冬氨酸的比例低于谷
氨酸的 20%,支持预
苯甲酸氨基转移酶活性。在相反方向,随着α-酮
戊二酸的浓度从1降低,与正向相当的反应速率没有变化。0 到 0.09 mᴍ。Arogenate 的表观 Km 为 0.8 mᴍ。正向反应不受包含
酪氨酸、苯丙
氨酸或色
氨酸的影响。连同在高粱中发现的
芳香酸脱氢酶 [3],这些数据表明,在高粱植物中,
酪氨酸通过转
氨基和芳构化从 prephenate