Amino acid composition, antioxidant property and angiotensin I-converting enzyme (ACE) inhibitory activity of micropeptides in skim milk powder
2011
Lei Cui | Mini Huang, Shanghai Jiao Tong Univ., 800 Dongchuan Rd., Shanghai, 200240, (Peoples' Republic of China). Dept. of Food Science and Engineering | Daxian Zhao, Shanghai Jiao Univ., Shanghai, 200240 (Peoples' Republic of China) | Yun Deng | Bingjun Qian | Li Zhang | Yali Luo | Qing Xiao Wu | Meng Zhang Wu, Shanghai Jiao Tong Univ., 800 Dongchuan Rd., Shanghai, 200240, (Peoples' Republic of China). Dept. of Food Science and Engineering.
The study evaluated the amino acid composition, and the antioxidant and antihypertensive characteristics of micropeptides in skim milk powder. Milk proteins were slightly destroyed during the production of skim milk powder based on results sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The skim milk powder was rehydrated and salted-out. After centrifugation, the supernatants were subjected to microfiltration and then separated with Superdox-30G column fractionation, producing three fractions (PF-1, PF-2 and PF-3). The molecular weight of fraction PF-3 was about 1.0 KDa with a yield of 10.9 plus or minus 0.73 mg/g skim milk powder. Fraction PF-3 at 10 mg/mL showed modest antioxidant activity with a 1.1 - diphenyl - 2 - picrylhydraxyl (DPPH) free radical scavenging rate of 36.69 plus or minus 0.92%. The inhibitory rate of the angiotensin I-converting enzyme (ACE) activity of PF-3 at a concentration of 3 mg/mL was about 20.12 plus or minus 7.59%. Fraction PF-3 was found to be rich in Gly, Phe, Leu, Glu and Asp, and its total hydrophobic amino acid content was as high as 50.53%, which may have contributed to the antioxidant and ACE-inhibitory activities.
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