Sugimoto Y, Yamada M
Poult Sci. 1986 Apr;65(4):789-94. doi: 10.3382/ps.0650789.
The wet weight and nitrogen content in the water soluble fraction and granule fraction of chicken egg yolk changed during embryonic development. Rapid decreases between Days 14 and 16 were the largest changes observed. When protein components in the soluble and granule fractions of yolk from developing eggs were analyzed by polyacrylamide gel electrophoresis under denaturing conditions, the intensities of bands of some high molecular-weight proteins decreased during incubation, while smaller proteins increased. Most of such changes were observed after Day 16. The activities of proteinases and hydrolases assayed with protein substrates or synthetic substrates at a neutral pH were higher in the yolk sac membrane than in yolk itself. A benzoyl-L-tyrosine ethyl ester hydrolase showed the highest specific activity among the enzymes examined in yolk sac membrane homogenates. Its activity increased after Day 5 of embryogenesis, and became maximum on Days 14 to 20. The data suggest that some of the yolk proteins are degraded by yolk sac membrane enzymes during the latter half of the incubation period.
鸡蛋黄中水溶性部分和颗粒部分的湿重及氮含量在胚胎发育过程中发生了变化。观察到的最大变化是在第14天至第16天之间迅速下降。当在变性条件下通过聚丙烯酰胺凝胶电泳分析发育中鸡蛋蛋黄的可溶性部分和颗粒部分中的蛋白质成分时，一些高分子量蛋白质条带的强度在孵化过程中降低，而较小的蛋白质增加。大多数此类变化在第16天之后观察到。在中性pH下用蛋白质底物或合成底物测定的蛋白酶和水解酶的活性在卵黄囊膜中高于卵黄本身。在所检测的卵黄囊膜匀浆中的酶中，苯甲酰-L-酪氨酸乙酯水解酶显示出最高的比活性。其活性在胚胎发生的第5天之后增加，并在第14天至第20天达到最大值。数据表明，在孵化后期，一些蛋黄蛋白被卵黄囊膜酶降解。
