菠菜叶片过氧体甘氨酸转氨酶初探

菠菜叶片过氧体可转变甘油酸或羟基丙酮酸成为丝氨酸。以甘氨酸为氨基供体时,完整过氧体的转变活性比破碎的约高2.5倍,这不是由于完整的膜包被使有效的羟基丙酮酸浓度增加,或由于膜破碎使辅助因子损失,也不是由于过氧体膜的甘氨酸主动运输系统的作用。结果显示,在过氧体中存在甘氨酸转氨酶,完整过氧体中高的转氨速度可能是由于甘氨酸转氨酶在完整的和破碎的过氧体中的构象或构型不同。

PRELIMINARY INVESTIGATION OF GLYCINE AMINOTRANSFERASE IN SPINACH LEAF PEROXISOMES

Glycerate or OH-pyruvate was converted into serine by spinach leaf peroxisomes.The rate of conversion in intact peroxisomes was about 2.5 times higher than that in broken peroxi- somes,with glycine as the NH_2-donor.This higher converting rate in intact peroxisomes was not due to the increase of available OH-pyruvate concentration in intact peroxisomes,or the loss of cofactors to the apoenzyme in broken peroxisomes,also not due to the effect of active transferring system of glycine in peroxisomal membrane.The results suggested that there is a glycine aminotransferase in spinach leaf peroxisomes,and the high converting rate in intact peroxisomes was probably due to the difference of conformation or configuration of the glycine aminotransferase between the intact peroxisomes and broken peroxisomes.