Kent R J, Lin R L, Sallach H J, Cohen P P
Proc Natl Acad Sci U S A. 1975 May;72(5):1712-6. doi: 10.1073/pnas.72.5.1712.
Glutamine-dependent carbanoyl phosphate synthase [ATP6carbamate phosphotransgerase (dephosphorylating), EC 2.7.2.9], aspartate transcarbamoylase (carbamoylphosphate: L-aspartate carbamoyltransferase, EC 2.1.3.2) and dihydroorotase (L-5,6-dihydroorotate amidohydrolase, EC 3.5.2.3), are copurified as a high-molicular-weight complex from extracts of unfertilized eggs of Rana catesbeiana. UTP is required to maintain the integrity of the complex during the last two purification steps. Removal of the nucleotide results in dissociation of the complex. Based on sedimentation behavior in glycerol gradients, the dissociated carbamoyl phosphate synthase has an apparent molecular weight of 260,000 +/- 20,000 and that of dihydroorotase is estimated at 280,000 +/- 20,000. Aspartate transcarbamoylase is broadly distributed over the gradient. The addition of ATP, 5-phosphoribosyl-1-pyrophosphate, Mg++, or inorganic phosphate to the dossociated complex results in the appearance of a peak of aspartate transcarbamoylase activity with an apparent molecular weight of 110,000 +/- 10,000. Icubation of a mixture of the dissociated enzymes with UTP and Mg++ leads to their reassociation into the high-molecular-weight complex.
谷氨酰胺依赖性氨甲酰磷酸合成酶[ATP：氨甲酰磷酸磷酸转移酶（去磷酸化），EC 2.7.2.9]、天冬氨酸转氨甲酰酶（氨甲酰磷酸：L-天冬氨酸氨甲酰转移酶，EC 2.1.3.2）和二氢乳清酸酶（L-5,6-二氢乳清酸酰胺水解酶，EC 3.5.2.3），从牛蛙未受精卵提取物中作为一种高分子量复合物共纯化得到。在最后两步纯化过程中，需要UTP来维持复合物的完整性。去除核苷酸会导致复合物解离。根据在甘油梯度中的沉降行为，解离后的氨甲酰磷酸合成酶的表观分子量为260,000±20,000，二氢乳清酸酶的表观分子量估计为280,000±20,000。天冬氨酸转氨甲酰酶在梯度中分布较广。向解离后的复合物中添加ATP、5-磷酸核糖-1-焦磷酸、Mg++或无机磷酸盐，会出现一个表观分子量为110,000±10,000的天冬氨酸转氨甲酰酶活性峰。将解离后的酶混合物与UTP和Mg++一起孵育，会导致它们重新结合成高分子量复合物。
