Smith T K
Proc Soc Exp Biol Med. 1985 Dec;180(3):538-43. doi: 10.3181/00379727-180-42214.
Experiments were conducted to determine the effect of feeding diets containing leucine-rich proteins on in vitro protein synthesis in porcine muscle. Swine (10 kg initial weight) were fed for 4 weeks diets composed mainly of corn gluten meal, corn and soybean meal, and containing a total of 2.00, 2.33, 2.92, 3.12, 3.53, and 4.01% leucine. At the end of the growing period, six swine fed each diet were killed and samples of biceps femoris, longissimus dorsi, and triceps brachii were excised. Incorporation of [14C]phenylalanine into newly synthesized protein was measured using a cell-free in vitro system following recombination of purified soluble protein and ribosomal fractions. The feeding of diets containing increasing amounts of leucine-rich protein increased the free leucine concentration in plasma and skeletal muscle. There was no significant effect of diet on incorporation of [14C]phenylalanine into muscle protein following simple recombination of soluble protein and ribosomal fractions from the same tissues. Combination of muscle soluble protein from animals fed 2.00% leucine with ribosomal fractions of animals fed increasing quantities of leucine-rich protein, however, indicated increased protein synthetic activity of the ribosomal fraction in all muscles tested. Protein synthetic activity of the soluble protein fraction was not affected by diet. It was concluded that the feeding of leucine-rich dietary proteins beyond requirements for maximal rate of growth can increase the protein synthetic potential of porcine muscle cells although whole body growth is depressed.
开展实验以确定饲喂富含亮氨酸蛋白质的日粮对猪肌肉体外蛋白质合成的影响。选用初始体重为10千克的猪，饲喂主要由玉米蛋白粉、玉米和豆粕组成的日粮4周，日粮中亮氨酸的总量分别为2.00%、2.33%、2.92%、3.12%、3.53%和4.01%。在生长期末，处死每种日粮饲喂的6头猪，并切除股二头肌、背最长肌和肱三头肌的样本。在将纯化的可溶性蛋白和核糖体组分重组后，使用无细胞体外系统测定[14C]苯丙氨酸掺入新合成蛋白质中的情况。饲喂富含亮氨酸蛋白质含量不断增加的日粮会使血浆和骨骼肌中的游离亮氨酸浓度升高。在将来自相同组织的可溶性蛋白和核糖体组分简单重组后，日粮对[14C]苯丙氨酸掺入肌肉蛋白中没有显著影响。然而，将饲喂2.00%亮氨酸的动物的肌肉可溶性蛋白与饲喂富含亮氨酸蛋白质数量不断增加的动物的核糖体组分相结合，结果表明在所有测试肌肉中核糖体组分的蛋白质合成活性均有所增加。日粮对可溶性蛋白组分的蛋白质合成活性没有影响。得出的结论是，饲喂超过最大生长速率所需量的富含亮氨酸的日粮蛋白，尽管整体生长受到抑制，但仍可提高猪肌肉细胞的蛋白质合成潜力。
