Herbert J D, Coulson R A
J Nutr. 1975 May;105(5):616-23. doi: 10.1093/jn/105.5.616.
Changes in plasma levels of amino acids derived from fed protein were determined by feeding crocodilians (Caiman crocodilus crocodilus and Alligator mississipiensis) 7.5 g protein/kg body weight and by monitoring the plasma free amino acids for several days. Zein and several other vegetable proteins produced no rise in plasma amino acids and were excreted intact in the feces. Casein and fish muscle were rapidly digested but produced little rise in plasma amino acids, and the increases showed no relationship to the composition of the protein fed. Gelatin feeding led to large increases in plasma amino acids that persisted for more than a week, and the resulting pattern was nearly identical to the composition of gelatin with the exception of aspartic and glutamic acids, and several animals died. Equivalent quantities of fish muscle protein were assimilated without difficulty by the crocodilians. Endogenous protein secreted into the gut apparently contributed little to the amino acid mixture absorbed.
通过给凯门鳄（Caiman crocodilus crocodilus）和密西西比鳄（Alligator mississipiensis）投喂每千克体重7.5克蛋白质，并监测血浆游离氨基酸数天，来测定源自所喂食蛋白质的血浆氨基酸水平变化。玉米醇溶蛋白和其他几种植物蛋白未使血浆氨基酸水平升高，而是完整地随粪便排出。酪蛋白和鱼肉迅速被消化，但血浆氨基酸水平几乎没有升高，且升高情况与所喂食蛋白质的组成无关。投喂明胶导致血浆氨基酸大幅增加，这种增加持续了一周多，除天冬氨酸和谷氨酸外，所产生的模式与明胶的组成几乎相同，并且有几只动物死亡。等量的鱼肉蛋白能被凯门鳄顺利吸收。分泌到肠道中的内源性蛋白质显然对所吸收的氨基酸混合物贡献很小。
