标题：Effects of Leucine/Isoleucine Ratio in Amino Acid Mixture-Diets Simulating Normal and High-Lysine Maize Proteins on Growth, Nitrogen Balance, and Tryptophan-Niacin Metabolism in Rats
期刊名称：Journal of Nutritional Science and Vitaminology
印刷版ISSN：0301-4800
电子版ISSN：1881-7742
出版年度：1982
卷号：28
期号：6
页码：609-620
DOI：10.3177/jnsv.28.609
出版社：Center for Academic Publications Japan
摘要：To re-evaluate nutritive values of opaque-2 (02) and brittle-2 opaque -2 (bt2O2) maize protein and to re-estimate Gopalan's hypothesis [Lancet, i, 954-957 (1960)] that pathogenesis of pellagra might be related with intake of excess leucine and with chronic consumption of maize or jowar which contains relative high leucine, rats were fed on synthetic diets composed of amino acid mixtures simulating the protein of normal and high-lysine maize, O2 and bt2O2 maize. In order to investigate the effect of intake of excess leucine, leucine was supplemented to 02 and bt2O2 diet at the level of 0.43 and 0.73%, respectively, to adjust the ratio of leucine to isoleucine to that of normal maize protein. Judging from body weight gains and carcass nitrogen of weanling rats fed on these diets, the protein quality (amino acid composition) of bt2O2 maize was 30% superior nutritionally to that of 02 maize, and body composition of bt2O2 diet group were similar to that of casein diet group. Leucine supplementation did not affect these values except for a significant de-crease in plasma valine levels. In young adult rats fed on leucine supplemented 02 diet, excretion of urinary nitrogen increased significantly compared with 02 diet alone, suggesting that a slight amino acid imbalance took place. But leucine supplementation altered neither N 1-methylnicotinamide level in urine nor total niacin levels in the liver and the brain. These results suggest that supplementation of leucine to a high lysine maize diet did not affect tryptophan and niacin metabolism in rats under these conditions.
关键词：high-lysine maize;protein quality;leucine/isoleucine ratio;nitrogen balance;body composition;tryptophan and niacin metabolism
