Department of Chemistry, College of Sciences, Shiraz University, Shiraz, Iran.
Hematology and Oncology Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
Sci Rep. 2020 Mar 4;10(1):3976. doi: 10.1038/s41598-020-60972-w.
The synthetic Angiotensin Converting Enzyme (ACE) inhibitors have side effects and hence demands for natural ACE inhibitors have been rising. The aim of this study is to purify and introduce natural ACE inhibitors extracted from Zizyphus jujuba fruits. Proteins from Zizyphus jujuba were lysed by trypsin, papain and their combination. Acquired peptides were purified and evaluated for ACE inhibitory activity. Peptide fractions with inhibitory activity were sequenced using tandem mass spectrometry. To elucidate the mode of peptide binding to ACE, homology modeling, molecular docking and molecular dynamics simulation were performed. Amino acid sequence of F2 and F4 peptides, which were the most active hydrolysates, were determined to be IER and IGK with the IC values of 0.060 and 0.072 mg/ml, respectively. Results obtained by computational analysis revealed that similar to the common ACE competitive inhibitors such as captopril, IER tripeptide binds to the enzyme active site, in vicinity of the zinc binding site, and occupies the S1 and S2' subsites. Binding occurs through hydrogen bonding with Gln293, Lys522, His524, Tyr531 and also several hydrophobic interactions. Collectively, these findings indicate that IER tripeptide inhibits the rabbit ACE enzyme through a competitive mechanism of inhibition with IC values in the millimolar range.
合成的血管紧张素转换酶（ACE）抑制剂具有副作用，因此对天然 ACE 抑制剂的需求不断增加。本研究旨在从枣果实中提取和介绍天然 ACE 抑制剂。用胰蛋白酶、木瓜蛋白酶及其组合裂解枣中的蛋白质。获得的肽段经纯化后，评估其对 ACE 抑制活性。用串联质谱法对具有抑制活性的肽段进行测序。为了阐明肽与 ACE 结合的模式，进行了同源建模、分子对接和分子动力学模拟。对活性最强的水解物 F2 和 F4 肽的氨基酸序列进行了测定，其 IC 值分别为 0.060 和 0.072mg/ml，分别为 IER 和 IGK。计算分析结果表明，与卡托普利等常见 ACE 竞争性抑制剂类似，IER 三肽与酶的活性位点结合，靠近锌结合位点，并占据 S1 和 S2'亚位点。结合通过与 Gln293、Lys522、His524、Tyr531 形成氢键以及几个疏水相互作用发生。综上所述，这些发现表明，IER 三肽通过竞争性抑制机制抑制兔 ACE 酶，其 IC 值在毫摩尔范围内。
