James K A, Hove E L
J Nutr. 1980 Sep;110(9):1736-44. doi: 10.1093/jn/110.9.1736.
The effectiveness of cystine supplementation in improving the nutritional quality of diets deficient in sulfur amino acids was investigated by measuring the weight gain and protein efficiency ratio of rats fed basal 10% protein diets and basal diets supplemented with either 2.0 g/kg DL-methionine or 4.0 g/kg L-cystine. Whereas methionine improved the weight gain of rats and the protein quality of all sources of dietary protein tested, cystine gave a positive response with diets containing lupin tops, casein, yeast and leaf protein concentrate but was ineffective for sweet lupin seed, soybean meal, broad beans and lentils. The ineffectiveness was observed as a general depression of weight gain and protein efficiency ratio. The depression was statistically significant for some diets containing lentils as the sole source of protein. The endogenous methionine and cystine contents of the diets were determined. and the ratios of cystine to methionine were correlated with the responses to supplementary cystine. Generally supplementary cystine was effective where the ratio was less than one and was ineffective where greater than one. The data are discussed in relation to the generally accepted concepts of the dietary methionine-cystine interrelationship.
通过测量喂食基础10%蛋白质日粮以及添加了2.0 g/kg DL-蛋氨酸或4.0 g/kg L-胱氨酸的基础日粮的大鼠的体重增加和蛋白质效率比，研究了补充胱氨酸对改善缺乏含硫氨基酸日粮营养质量的效果。虽然蛋氨酸提高了大鼠的体重增加以及所测试的所有膳食蛋白质来源的蛋白质质量，但胱氨酸对含有羽扇豆顶部、酪蛋白、酵母和叶蛋白浓缩物的日粮有积极反应，而对甜羽扇豆种子、豆粕、蚕豆和小扁豆则无效。观察到这种无效表现为体重增加和蛋白质效率比普遍降低。对于一些以小扁豆作为唯一蛋白质来源的日粮，这种降低在统计学上具有显著性。测定了日粮中内源性蛋氨酸和胱氨酸的含量，并将胱氨酸与蛋氨酸的比率与补充胱氨酸的反应进行了关联。一般来说，当该比率小于1时补充胱氨酸有效，而大于1时则无效。结合膳食蛋氨酸 - 胱氨酸相互关系的普遍接受概念对这些数据进行了讨论。
