In the present study, whey protein concentrate (WPC-80) and β-lactoglobulin were hydrolyzed with a noncommercial serine protease isolated from Asian pumpkin (Cucurbita ficifolia). Hydrolysates were further fractionated by ultrafiltration using membranes with cut-offs equal 3 and 10 kDa. Peptide fractions of molecular weight lower than 3 and 3–10 kDa were further subjected to the RP-HPLC. Separated preparations were investigated for their potential as the natural inhibitors of dipeptidyl peptidase (DPP-IV), α-glucosidase and angiotensin converting enzyme (ACE). WPC-80 hydrolysate showed higher inhibitory activities against the three tested enzymes than β-lactoglobulin hydrolysate. Especially high biological activities were exhibited by peptide fractions of molecular weight lower than 3 kDa, with ACE IC50 <0.64 mg/mL and DPP-IV IC50 <0.55 mg/mL. This study suggests that peptides generated from whey proteins may support postprandial glycemia regulation and blood pressure maintenance, and could be used as functional food ingredients in the diet of patients with type 2 diabetes.

中文翻译：

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亚洲南瓜（Cucurbita ficifolia）丝氨酸蛋白酶水解乳清蛋白对二肽基肽酶 (DPP)-IV、α-葡萄糖苷酶和血管紧张素转化酶 (ACE) 抑制活性的评价。

在本研究中，乳清蛋白浓缩物 (WPC-80) 和 β-乳球蛋白用从亚洲南瓜 ( Cucurbita ficifolia) 中分离的非商业丝氨酸蛋白酶水解）。使用截留值为 3 和 10 kDa 的膜通过超滤进一步分离水解产物。分子量低于 3 和 3-10 kDa 的肽级分进一步进行 RP-HPLC。研究了分离的制剂作为二肽基肽酶 (DPP-IV)、α-葡萄糖苷酶和血管紧张素转化酶 (ACE) 的天然抑制剂的潜力。WPC-80 水解物对三种测试酶的抑制活性高于 β-乳球蛋白水解物。分子量低于 3 kDa 的肽级分表现出特别高的生物活性，ACE IC50 <0.64 mg/mL 和 DPP-IV IC50 <0.55 mg/mL。这项研究表明，由乳清蛋白产生的肽可能支持餐后血糖调节和血压维持，