Kumada Yoichi, Hashimoto Naoya, Hasan Fida, Terashima Masaaki, Nakanishi Kazuhiro, Jungbauer Alois, Katoh Shigeo
Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
J Biotechnol. 2007 Aug 31;131(2):144-9. doi: 10.1016/j.jbiotec.2007.06.003. Epub 2007 Jun 19.
Angiotensin I converting enzyme (ACE)-inhibitory peptides were screened from a random peptide-displayed phage library using ACE-coupled liposomes. Among four kinds of inhibitory peptides selected by biopanning with two different elution strategies, a peptide (LSTLRSFCA) showed the highest inhibitory activity with an IC(50) value of 3microM. By measuring inhibitory activities of fragments of the peptide, it was found that the RSFCA region was a functional site to inhibit strongly the ACE catalytic activity, and particularly both Arg and Cys residues were essential for the strong inhibitory activity. The inhibitory activity of RRFCA was slightly increased, while that of the RSFRA, in which the Cys residue was replaced by Arg, was decreased to greater extent in comparison with the inhibitory activity of RSFCA. Taking into account the results obtained from the SPOT analysis, it was suggested that the Arg and Phe residues in RSFCA were important for a specific interaction with ACE, and the Cys residue inhibited the ACE activity. The cystein-based ACE-inhibitory peptides have not been isolated from processed food materials. These findings suggested that the biopanning method utilizing protein-coupled liposomes and random peptide libraries might have a possibility to screen new functional peptides that are not found in processed food materials.
利用与血管紧张素转换酶（ACE）偶联的脂质体从随机肽展示噬菌体文库中筛选ACE抑制肽。在采用两种不同洗脱策略通过生物淘选选出的四种抑制肽中，一种肽（LSTLRSFCA）表现出最高的抑制活性，IC（50）值为3μM。通过测定该肽片段的抑制活性，发现RSFCA区域是强烈抑制ACE催化活性的功能位点，特别是Arg和Cys残基对于强抑制活性至关重要。与RSFCA的抑制活性相比，RRFCA的抑制活性略有增加，而Cys残基被Arg取代的RSFRA的抑制活性则大幅降低。考虑到SPOT分析的结果，提示RSFCA中的Arg和Phe残基对于与ACE的特异性相互作用很重要，而Cys残基抑制ACE活性。基于半胱氨酸的ACE抑制肽尚未从加工食品原料中分离出来。这些发现表明，利用蛋白质偶联脂质体和随机肽文库的生物淘选方法可能有机会筛选出加工食品原料中未发现的新型功能肽。
