Krieghoff E, Bergner H
Arch Tierernahr. 1976 Sep;25(7):495-503.
Experimental rats received purified or semisynthetic diets containing 10% or 6% crude protein (Soya protein). These were supplemented with 0.1% or 0.2% L-, D- or DL methionine. After a 5-day feeding period the animals were injected 35S-DL-methionine. For 48 hrs after 35S administration the pattern of urinary 35S excretion was traced. Neither the level of protein does not the configuration of the methionine supplemented nor the level of methionine supplementation were found to influence urinary 35S excretion in any way. Amino acid imbalance as induced by supplementation of 5% DL threonine produced a highly significant increase in the rate of 35S excretion on the 1st day of experiment. The results obtained suggest the conclusion that any determination of methionine requirements based on metabolic data should leave out from consideration values on the level of urinary 35S excretion obtained on the first day of experiment, as these are dependent on amino acid transport rather than on protein metabolism.
实验大鼠接受含有10%或6%粗蛋白（大豆蛋白）的纯化或半合成饮食。这些饮食补充了0.1%或0.2%的L-、D-或DL-蛋氨酸。在5天的喂养期后，给动物注射35S-DL-蛋氨酸。在给予35S后的48小时内，追踪尿液中35S排泄的模式。未发现蛋白质水平、补充蛋氨酸的构型以及蛋氨酸补充水平以任何方式影响尿液中35S的排泄。补充5% DL-苏氨酸诱导的氨基酸失衡在实验的第1天使35S排泄率显著增加。所获得的结果表明这样的结论：基于代谢数据对蛋氨酸需求量的任何测定都应排除实验第一天获得的尿液中35S排泄水平的值，因为这些值取决于氨基酸转运而非蛋白质代谢。
