Influence of Amino Acid Compositions and Peptide Profiles on Antioxidant Capacities of Two Protein Hydrolysates from Skipjack Tuna (Katsuwonus pelamis) Dark Muscle.
Influence of amino acid compositions and peptide profiles on antioxidant capacities of two protein hydrolysates from skipjack tuna (Katsuwonus pelamis) dark muscle was investigated. Dark muscles from skipjack tuna were hydrolyzed using five separate proteases, including pepsin, trypsin, Neutrase, papain and Alcalase. Two hydrolysates, ATH and NTH, prepared using Alcalase and Neutrase, respectively, showed the strongest antioxidant capacities and were further fractionated using ultrafiltration and gel filtration chromatography. Two fractions, Fr.A3 and Fr.B2, isolated from ATH and NTH, respectively, showed strong radical scavenging activities toward 2,2-diphenyl-1-picrylhydrazyl radicals (EC50 1.08% ± 0.08% and 0.98% ± 0.07%), hydroxyl radicals (EC50 0.22% ± 0.03% and 0.48% ± 0.05%), and superoxide anion radicals (EC50 1.31% ± 0.11% and 1.56% ± 1.03%) and effectively inhibited lipid peroxidation. Eighteen peptides from Fr.A3 and 13 peptides from Fr.B2 were isolated by reversed-phase high performance liquid chromatography, and their amino acid sequences were determined. The elevated antioxidant activity of Fr.A3 might be due to its high content of hydrophobic and aromatic amino acid residues (181.1 and 469.9 residues/1000 residues, respectively), small molecular sizes (3-6 peptides), low molecular weights (524.78 kDa), and amino acid sequences (antioxidant score 6.11). This study confirmed that a smaller molecular size, the presence of hydrophobic and aromatic amino acid residues, and the amino acid sequences were the key factors that determined the antioxidant activities of the proteins, hydrolysates and peptides. The results also demonstrated that the derived hydrolysates and fractions from skipjack tuna (K. pelamis) dark muscles could prevent oxidative reactions and might be useful for food preservation and medicinal purposes.
National Engineering Research Center of Marine Facilities Aquaculture, School of Marine Science and Technology, Zhejiang Ocean University, 1st Haidanan Road, Changzhi Island, Lincheng, Zhoushan 316022, China. chichangfeng@hotmail.com.
Chang-Feng
CF
Chi
National Engineering Research Center of Marine Facilities Aquaculture, School of Marine Science and Technology, Zhejiang Ocean University, 1st Haidanan Road, Changzhi Island, Lincheng, Zhoushan 316022, China. moonriveryue@163.com.
Fa-Yuan
FY
Hu
Zhejiang Provincial Engineering Technology Research Center of Marine Biomedical Products, School of Food and Pharmacy, Zhejiang Ocean University, 1st Haidanan Road, Changzhi Island, Lincheng, Zhoushan 316022, China. wangbin4159@hotmail.com.
Bin
B
Wang
Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. zlibb@ust.hk.
Zhong-Rui
ZR
Li
Zhejiang Provincial Engineering Technology Research Center of Marine Biomedical Products, School of Food and Pharmacy, Zhejiang Ocean University, 1st Haidanan Road, Changzhi Island, Lincheng, Zhoushan 316022, China. lisa8919@163.com.
Hong-Yu
HY
Luo
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001713:Biphenyl Compounds / Q000378:metabolism; D016166:Free Radical Scavengers / Q000378:metabolism; D006868:Hydrolysis; D015227:Lipid Peroxidation / Q000502:physiology; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D010851:Picrates / Q000378:metabolism; D011492:Protein Hydrolysates / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014413:Tuna / Q000378:metabolism*
D000596:Amino Acids; D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010455:Peptides; D010851:Picrates; D011492:Protein Hydrolysates; D013481:Superoxides; C004931:1,1-diphenyl-2-picrylhydrazyl