Hsu Feng-Lin, Lin Yaw-Huei, Lee Mei-Hsien, Lin Chien-Liang, Hou Wen-Chi
Graduate Institute of Pharmacognosy Science, Taipei Medical University, Taipei 110, Taiwan, Republic of China.
J Agric Food Chem. 2002 Oct 9;50(21):6109-13. doi: 10.1021/jf0203287.
Dioscorin, the tuber storage protein of yam (Dioscorea alata cv. Tainong No. 1), was purified to homogeneity by DE-52 ion-exchange chromatography. This purified dioscorin was shown by spectrophotometric methods to inhibit angiotensin converting enzyme (ACE) in a dose-dependent manner (12.5-750 microg, respectively, 20.83-62.5% inhibitions) using N-[3-(2-furyl)acryloyl]-Phe-Gly-Gly (FAPGG) as substrates. The 50% inhibition (IC(50)) of ACE activity was 6.404 microM dioscorin (250 microg corresponding to 7.81 nmol) compared to that of 0.00781 microM (0.0095 nmol) for captopril. The commercial bovine serum albumin and casein (bovine milk) showed less ACE inhibitory activity. The use of qualitative TLC also showed dioscorin as ACE inhibitors. Dioscorin showed mixed noncompetitive inhibitions against ACE; when 31.25 microg of dioscorin (0.8 microM) was added, the apparent inhibition constant (K(i)) was 2.738 microM. Pepsin was used for dioscorin hydrolysis at 37 degrees C for different times. It was found that the ACE inhibitory activity was increased from 51.32% to about 75% during 32 h hydrolysis. The smaller peptides were increased with increasing pepsin hydrolytic times. Dioscorin and its hydrolysates might be a potential for hypertension control when people consume yam tuber.
薯蓣球蛋白是山药（参薯品种台农1号）块茎中的贮藏蛋白，通过DE - 52离子交换色谱法纯化至同质。采用N - [3 - (2 - 呋喃基)丙烯酰基]-苯丙氨酸-甘氨酸-甘氨酸（FAPGG）作为底物，通过分光光度法表明，这种纯化的薯蓣球蛋白以剂量依赖方式抑制血管紧张素转换酶（ACE）（分别为12.5 - 750微克，抑制率为20.83 - 62.5%）。与卡托普利的0.00781微摩尔（0.0095纳摩尔）相比，ACE活性的50%抑制率（IC50）为6.404微摩尔薯蓣球蛋白（250微克相当于7.81纳摩尔）。市售牛血清白蛋白和酪蛋白（牛乳）显示出较低的ACE抑制活性。定性薄层层析的结果也表明薯蓣球蛋白具有ACE抑制活性。薯蓣球蛋白对ACE表现出混合型非竞争性抑制；当加入31.25微克薯蓣球蛋白（0.8微摩尔）时，表观抑制常数（Ki）为2.738微摩尔。在37℃下用胃蛋白酶对薯蓣球蛋白进行不同时间的水解。发现在32小时水解过程中，ACE抑制活性从51.32%增加到约75%。随着胃蛋白酶水解时间的增加，较小的肽段增多。当人们食用山药块茎时，薯蓣球蛋白及其水解产物可能具有控制高血压的潜力。
