孕酮与大鼠泌乳生成过程中乳糖生物合成途径的代谢调控

Progesterone and the metabolic control of the lactose biosynthetic pathway during lactogenesis in the rat.

Murphy G, Ariyanayagam A D, Kuhn N J

Biochem J. 1973 Dec;136(4):1105-16. doi: 10.1042/bj1361105.

Abstract

Lactogenesis was initiated in pregnant rats by ovariectomy, thereby causing progesterone withdrawal, after which the mammary tissue was analysed for contents of enzymes and metabolites concerned with the biosynthesis of lactose. 2. Lactose synthesis increased about 126-fold with little or no accompanying change in the contents of most metabolic intermediates or in the adenine nucleotide energy charge. 3. Comparison of mass-action ratios with equilibrium constants showed that phosphoglucomutase (EC 2.7.5.1), UDP-glucose pyrophosphorylase (EC 2.7.7.9) and UDP-glucose epimerase (EC 5.1.3.2.) catalysed reactions close to equilibrium. Nucleoside diphosphokinase (EC 2.7.4.6.) activity was very high and probably equilibrates the UTP-UDP and ATP-ADP couples. Lactose synthetase and hexokinase (EC 2.7.1.1) appeared to catalyse rate-limiting reactions. 4. Large increases were seen of UDP-glucose pyrophosphorylase (5-fold), lactose synthetase A protein (3.8-fold) and alpha-lactalbumin (28-fold), but not of hexokinase, phosphoglucomutase, UDP-glucose epimerase, nucleoside diphosphokinase or glucose 6-phosphate dehydrogenase (EC 1.1.1.49) activities. 5. It appeared that the increased lactose synthesis was largely accounted for by the increased lactose synthetase A protein activity and alpha-lactalbumin.

摘要

通过切除怀孕大鼠的卵巢启动泌乳过程，从而导致孕酮撤退，之后分析乳腺组织中与乳糖生物合成相关的酶和代谢物含量。2. 乳糖合成增加了约126倍，而大多数代谢中间体的含量或腺嘌呤核苷酸能量电荷几乎没有伴随变化。3. 将质量作用比与平衡常数进行比较表明，磷酸葡萄糖变位酶（EC 2.7.5.1）、UDP-葡萄糖焦磷酸化酶（EC 2.7.7.9）和UDP-葡萄糖差向异构酶（EC 5.1.3.2.）催化的反应接近平衡。核苷二磷酸激酶（EC 2.7.4.6.）活性非常高，可能使UTP-UDP和ATP-ADP偶联达到平衡。乳糖合成酶和己糖激酶（EC 2.7.1.1）似乎催化限速反应。4. UDP-葡萄糖焦磷酸化酶（5倍）、乳糖合成酶A蛋白（3.8倍）和α-乳白蛋白（28倍）的活性大幅增加，但己糖激酶、磷酸葡萄糖变位酶、UDP-葡萄糖差向异构酶、核苷二磷酸激酶或葡萄糖6-磷酸脱氢酶（EC 1.1.1.49）的活性没有增加。5. 似乎乳糖合成增加主要是由乳糖合成酶A蛋白活性和α-乳白蛋白增加所致。