Suzuki Y, Erickson R H, Sedlmayer A, Chang S K, Ikehara Y, Kim Y S
Gastrointestinal Research Laboratory, Department of Veterans Affairs Medical Center, San Francisco 94121.
Am J Physiol. 1993 Jun;264(6 Pt 1):G1153-9. doi: 10.1152/ajpgi.1993.264.6.G1153.
The small intestinal brush-border membrane contains several peptidases that are involved in the hydrolysis of dietary peptides containing proline. A high-proline (gelatin) diet was administered to one of several groups of rats to study its possible regulatory effect on levels of two prolyl peptidases, namely angiotensin-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP IV). Groups of rats were maintained on isocaloric diets containing either low (4%), normal (17%), or high (50%) protein (casein) or high (50%) gelatin. After 7 days, brush-border membranes and total RNA were prepared from the small intestine. ACE activity was 3- to 10-fold higher in brush-border membranes from the gelatin group compared with the low-protein group. DPP IV exhibited a three- to sixfold increase. Immunoblot analysis of brush-border membrane-associated ACE protein indicated a six- to eightfold increase in the high-gelatin group. There was also a 1.5- to 3-fold increase in steady-state levels of ACE and DPP IV mRNA. These results suggest that a diet high in proline (gelatin) is particularly effective in increasing intestinal levels of these two enzymes.
小肠刷状缘膜含有几种肽酶，这些肽酶参与含脯氨酸的膳食肽的水解。给几组大鼠中的一组喂食高脯氨酸（明胶）饮食，以研究其对两种脯氨酰肽酶（即血管紧张素转换酶（ACE）和二肽基肽酶IV（DPP IV））水平的可能调节作用。将几组大鼠维持在含有低（4%）、正常（17%）或高（50%）蛋白质（酪蛋白）或高（50%）明胶的等热量饮食中。7天后，从小肠制备刷状缘膜和总RNA。与低蛋白组相比，明胶组刷状缘膜中的ACE活性高3至10倍。DPP IV增加了三至六倍。对刷状缘膜相关ACE蛋白的免疫印迹分析表明，高明胶组增加了六至八倍。ACE和DPP IV mRNA的稳态水平也增加了1.5至3倍。这些结果表明，高脯氨酸（明胶）饮食在提高这两种酶的肠道水平方面特别有效。
