Abstract

Angiotensin-I converting enzyme (ACE) inhibitors are widely used to control hypertension. In this study, protein hydrolysates from shiitake mushroom were hydrolyzed to prepare ACE-inhibitory peptides. Optimum process conditions for the hydrolysis of shiitake mushrooms using Alcalase were optimized using response surface methodology. Monitoring was conducted to check the degree of hydrolysis (DH) and ACE inhibitory activity. In the results, the optimum condition with the highest DH value of 28.88% was 50.2 °C, 3-h hydrolysis time, and 1.16 enzyme/substrate ratios. The highest ACE inhibitory activity (IC₅₀ of 0.33 μg/mL) was under 47 °C, 3 h 28 min hydrolysis time, and 0.59 enzyme/substrate ratios. The highest activity was fractionated into 5 ranges of molecular weight, and the fraction below 0.65 kDa showed the highest activity with IC₅₀ of 0.23 μg/mL. This fraction underwent purification using RP-HPLC, meanwhile the peak which offered a retention time of about 37 min showed high ACE inhibitory activity. Mass spectrometry identified the amino acid sequence of this peak as Lys-Ile-Gly-Ser-Arg-Ser-Arg-Phe-Asp-Val-Thr (KIGSRSRFDVT), with a molecular weight of 1265.43 Da. The synthesized variant of this peptide produced an ACE inhibitory activity (IC₅₀) of 37.14 μM. The peptide KIGSRSRFDVT was shown to serve as a non-competitive inhibitor according to the Lineweaver–Burk plot findings. A molecular docking study was performed, which showed that the peptide binding occurred at an ACE non-active site. The findings suggest that peptides derived from shiitake mushrooms could serve either as useful components in pharmaceutical products, or in functional foods for the purpose of treating hypertension.

Graphic abstract

中文翻译：

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来自香菇（香菇）的血管紧张素-I转化酶抑制肽

摘要

血管紧张素-I 转换酶 (ACE) 抑制剂广泛用于控制高血压。在这项研究中，来自香菇的蛋白质水解物被水解以制备 ACE 抑制肽。使用响应面法优化使用 Alcalase 水解香菇的最佳工艺条件。进行监测以检查水解程度（DH）和ACE抑制活性。结果表明，DH值为28.88%的最佳条件为50.2 ℃、3 h水解时间和1.16酶/底物比。最高的 ACE 抑制活性（IC ₅₀0.33 μg/mL）在 47 °C、3 小时 28 分钟水解时间和 0.59 酶/底物比率下进行。最高活性被分成5个分子量范围，低于0.65 kDa的部分表现出最高活性，IC ₅₀为0.23 μg/mL。该级分使用 RP-HPLC 进行纯化，同时提供约 37 分钟保留时间的峰显示出高 ACE 抑制活性。质谱鉴定该峰的氨基酸序列为Lys-Ile-Gly-Ser-Arg-Ser-Arg-Phe-Asp-Val-Thr (KIGSRSRFDVT)，分子量为1265.43 Da。该肽的合成变体产生 ACE 抑制活性（IC ₅₀) 的 37.14 μM。根据 Lineweaver-Burk 图的发现，肽 KIGSRSRFDVT 显示为非竞争性抑制剂。进行了分子对接研究，结果表明肽结合发生在 ACE 非活性位点。研究结果表明，从香菇中提取的肽既可以作为药品中的有用成分，也可以作为用于治疗高血压的功能性食品中的有用成分。

图形摘要