Polypeptide mixture with oxidation resistance and DPP-IV inhibitory activity and preparation method of polypeptide mixture

The invention discloses a polypeptide mixture with oxidation resistance and DPP-IV (Dipeptidyl Peptidase IV) inhibitory activity. The amino acid sequences of the polypeptide mixture comprise HLVDEPQNLIK, DDQNPHSSN and DDEVDVDGTVEEDLGK. The polypeptide mixture is derived from whey protein. The preparation method of the polypeptide mixture comprises the following steps: step 1, carrying out ultrahigh-pressure treatment on a whey protein isolate solution with the concentration of 1% to obtain an ultrahigh-pressure whey protein isolate solution; step 2, adjusting the pH value of the ultrahigh-pressure whey protein isolate solution in the step 1 to 2.0-3.0, adding pepsase and acid protease, carrying out heating hydrolysis and enzyme deactivation, carrying out centrifugation to obtain a supernatant, and carrying out freeze drying after rotary evaporation to obtain a polypeptide mixture crude product; and step 3, adjusting the concentration of the polypeptide mixture crude product to 1mg/mL, and separating and purif