脱脂南极磷虾粉中降血糖与抗氧化肽的分离纯化与鉴定

食源性二肽基肽酶IV（dipeptidyl peptidase-IV，DPP-IV）抑制肽和抗氧化肽分别有助于清除体内自由基和调节机体血糖。为实现脱脂南极磷虾粉的高值化利用，为糖尿病治疗寻找新方法，从脱脂南极磷虾粉酶解产物中制备DPP-IV抑制肽和抗氧化肽。使用碱性蛋白酶、中性蛋白酶和胰酶水解脱脂南极磷虾粉，探究时间与水解度、活性、产率的关系，并分离纯化多肽，最后通过分子对接确定抑制作用位点。结果表明，酶解液经超滤、Sephadex G15分离纯化和液相-质谱联用技术鉴定后，得到了4条具有DPP-IV抑制和抗氧化作用的肽，氨基酸序列分别为WPPLSPFRCPR、IPDWFLNRQ、FLWLKKTPLPL和DTVPWFPR。其中IPDWFLNRQ具备较高DPP-IV抑制活性，DPP-IV抑制活性IC50值为（0.616±0.097) mmol/L；WPPLSPFRCPR具有较高的抗氧化活性，DPPH EC50值为(0.0983±0.011) mmol/L，ABTS EC50值为(0.116±0.073) mmol/L。分子对接结果表明这4种肽主要通过氢键与DPP-IV活性中心及其以外的位点相结合，从而达到抑制DPPP-IV活性的作用。本研究基于脱脂南极磷虾粉制备食源性DPP-IV抑制肽和抗氧化肽，以期为南极磷虾粉的开发利用提供理论依据。

Purification and identification of antidiabetogenic and antioxidant peptide from defatted Antarctic krill powder hydrolysates

Food-derived dietary dipeptidyl peptiase-IV (DPP-IV) inhibitory peptides and antioxidant peptides can contribute to scavenge free radicals in vivo and regulate blood sugar. In order to realize the high-value application of the defatted Antarctic krill powder and explore new ways to cure diabetes, DPP-IV inhibitory peptide and antioxidant peptide were prepared from defatted Antarctic krill powder by enzymolysis with alkaline protease, neutral protease and pancreatic enzyme. The relationships between time and hydrolysis degree, bioactivity and peptide yield rate respectively were investigated. Polypeptide was purified and analyzed, and the inhibitory sites were ascertained by molecular docking. The results illustrated that four peptides with both DPP-IV inhibitory activity and antioxidant activity were acquired by ultrafiltration, Sephadex G15 separation and purification and liquid-mass spectrometry, whose amino acid sequences were WPPLSPFRCPR, IPDWFLNRQ, FLWLKKTPLPL and DTVPWFPR, respectively. IPDWFLNRQ had the highest DPP-IV inhibitory activity among these four peptides, and the IC50 value of which was (0.616±0.98 mM). WPPLSPFRCPR possessed the higher antioxidant activity, whose DPPH EC50 was (0.0983±0.011 mM) and ABTS EC50 was (0.116±0.073 mM). Molecular docking results demonstrated that these four peptides mainly bind to the active center of DPP-IV and other sites through hydrogen, resulting in achieving inhibitory effect. This study prepared food-borne DPP-IV inhibitory and antioxidant peptides based on the defatted Antarctic krill powder, which provided references for the development and utilization of aquatic protein-derived hypoglycemic functional food and the research of novel hypoglycemic and antioxidant peptides.