Bioactive peptides derived from food proteins are becoming increasingly popular due to the growing awareness of their health-promoting properties. The structure and mechanism of anti-cancer action of pentapeptide Glu-Gln-Arg-Pro-Arg (EQRPR) derived from a rice bran protein are not known. Theoretical and experimental methods were employed to fill this gap. The conformation analysis of the EQRPR pentapeptide was performed first and the obtained lowest energy conformer was optimized. The experimental structural data obtained by FTIR and CD spectroscopies agree well with the theoretical results. d-isomer introduced one-by-one to each position and all D-isomers of the peptide were also examined for its possible anti-proteolytic and activity enhancement properties. The molecular docking revealed avid binding of the pentapeptide to the integrins α₅β₁ and α_IIbβ₃, with K_d values of 90 nM and 180 nM, respectively. Moreover, the EQRPR and its D-isomers showed strong binding affinities to apo- and holo-forms of M^pro, spike glycoprotein, ACE2, and dACE2. The predicted results indicate that the pentapeptide may significantly inhibit SARS-CoV-2 infection. Thus, the peptide has the potential to be the leading molecule in the drug discovery process as having multifunctional with diverse biological activities.

由于人们越来越认识到源自食品蛋白质的生物活性肽具有促进健康的特性，因此它们变得越来越受欢迎。源自米糠蛋白的五肽 Glu-Gln-Arg-Pro-Arg (EQRPR) 的结构和抗癌作用机制尚不清楚。采用理论和实验方法来填补这一空白。首先对EQRPR五肽进行构象分析，并对获得的最低能量构象进行优化。 FTIR和CD光谱获得的实验结构数据与理论结果非常吻合。 d-异构体被一一引入到每个位置，并且还检查了肽的所有D-异构体可能的抗蛋白水解和活性增强特性。分子对接显示五肽与整合素 α ₅ β ₁和 α _IIb β ₃强烈结合，K _d值分别为 90 nM 和 180 nM。此外，EQRPR 及其 D 异构体对 M ^pro 、刺突糖蛋白、ACE2 和 dACE2 的 apo 形式和全息形式表现出很强的结合亲和力。预测结果表明五肽可能显着抑制SARS-CoV-2感染。因此，该肽具有多功能且具有多种生物活性，有可能成为药物发现过程中的主导分子。