二、以下題組與Covid-19疫相關,請依序作答。(共50分

6. Lu et al. used a comparative molecular field analysis (CoMFA) model to show a positive correlation between C, M, the bulky C-terminal amino acid residue (R), the negatively charged group around sulfur-containing amino acids, and the antioxidant activity of a nanopeptide with the SYPTECRMR sequence obtained from sesame protein. The authors indicate that sulfur-containing amino acids (C, M) as well as steric and electrostatic factors determine the antioxidant activity of SYPTECRMR. Moreover, Zhang et al. reported that VEVYLPR and VVEVYLPR peptides obtained from egg- white protein exhibited lower antioxidant activity than VYLPR, which explains the fact that the position of glutamate
(E) in VEVYLPR and VVEVYLPR may affect their antioxidant activity. Zhang et al. concluded that valine at the N-terminus of VYLPR might be helpful to enhance the antioxidant activity of this peptide. Yang et al. showed that the crucial antiradical activity against ABTS+• of a novel peptide ATVY was dependent on Tyr positions in the N-terminus. In turn, Sheng et al. reported that the presence of antioxidant amino acids (W, Y, and M) did not determine the cellular antioxidative effect of peptides. On the other hand, Matsui et al. concluded that the antioxidant activities of tyrosine containing peptides GYG, GYYG, and YGGY varied, depending on the characteristics of ROS and/or RNS. The author showed that the number and position of Y in the peptides did not affect the antioxidant activity against the ClO− ion, whereas the Tyr position was an important factor for the activity against ONO2 −. In the case of ROO• , the number of Tyr residues influenced the antioxidant activity, while its position did not have a significant effect. [Adopted from   Foods 2020, 9, 846 ]