Berger J, Schneeman B O
Department of Nutrition, University of California, Davis 95616.
J Nutr. 1988 Jun;118(6):723-8. doi: 10.1093/jn/118.6.723.
Rats were fed test meals containing 23% protein as casein (C), soy protein isolate (SPI) or egg white (EW) to assess effects of dietary protein sources on te amount of zinc and carboxypeptidase (CP, CPA, CPB) activity in the small intestinal contents. Groups of six rats each were killed at 1, 2.5 and 5 h postprandial and six rats fasted for 19 h served as a 0 time control. Consumption of a test meal increased the weight of small intestinal contents at 1 and 2.5 h compared with unfed animals and in a similar manner for all three protein sources. However, at various times during the postprandial period differences in the level of zinc and CP activity within the small intestinal contents among the three dietary protein sources were observed. Both the SPI and EW groups had significantly higher levels of CPA and CPB activity at 1 h postprandial than the C group. Only in the SPI group was the intestinal level of zinc increased at 1 and 2.5 h compared with the unfed group. At 1 and 2.5 h postprandial intestinal zinc was significantly higher in the SPI group than in the C and EW groups. The results indicate that the disappearance of zinc from the intestine is delayed in rats fed SPI, probably because of the presence of phytate.
给大鼠喂食含23%酪蛋白（C）、大豆分离蛋白（SPI）或蛋清（EW）的试验餐，以评估膳食蛋白质来源对小肠内容物中锌含量和羧肽酶（CP、CPA、CPB）活性的影响。每组6只大鼠，分别在餐后1小时、2.5小时和5小时处死，6只禁食19小时的大鼠作为0小时对照组。与未喂食的动物相比，食用试验餐使小肠内容物重量在餐后1小时和2.5小时增加，且三种蛋白质来源的情况相似。然而，在餐后不同时间，观察到三种膳食蛋白质来源的小肠内容物中锌水平和CP活性存在差异。SPI组和EW组在餐后1小时的CPA和CPB活性水平均显著高于C组。仅SPI组在餐后1小时和2.5小时时，小肠锌水平与未喂食组相比有所增加。在餐后1小时和2.5小时，SPI组的小肠锌含量显著高于C组和EW组。结果表明，喂食SPI的大鼠小肠中锌的消失延迟，可能是由于植酸盐的存在。
