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Identification of short peptide sequences in the nanofiltration permeate of a bioactive whey protein hydrolysate
Le Maux, Solene Nongonierma, Alice B. Murray, Brian A. Kelly, Philip Fitzgerald, Richard J.
Le Maux, Solene
Nongonierma, Alice B.
Murray, Brian A.
Kelly, Philip
Fitzgerald, Richard J.
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16/09/2015
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Le Maux, S., Nongonierma, A.B., Murray, B., Kelly, P.M.& FitzGerald, R.J., Identification of short peptide sequences in the nanofiltration permeateof a bioactive whey protein hydrolysate, Food Research International (2015), 77(3), 534-539, doi:10.1016/j.foodres.2015.09.012
Abstract
Short peptides in food protein hydrolysates are of significant interest as they may be highly bioactive whilst also being bioavailable. A dipeptidyl peptidase IV (DPP-IV) inhibitory whey protein hydrolysate (WPH) was fractionated using nanofiltration (NF) with a 200 Da MWCO membrane. The DPP-IV half maximal inhibitory concentration of the NF permeate (IC50 = 0.66 ± 0.08 mg protein equivalent mL− 1) was significantly more potent (P > 0.05) than that of the starting WPH (IC50 = 0.94 ± 0.24 mg protein equivalent mL− 1) and associated retentate (IC50 = 0.82 ± 0.13 mg protein equivalent mL− 1). This confirmed the contribution of short peptides within the NF permeate to the overall DPP-IV inhibitory activity. An hydrophilic interaction liquid chromatography (HILIC-) and reverse-phase (RP-) liquid chromatography tandem mass spectrometry (LC–MS/MS) strategy, based on two retention time models, allowed detection of eight free amino acids and eight di- to tetrapeptides in the NF permeate. The potential sequences of the peptides within the NF permeate were then ranked on the basis of their highest probability of occurrence. A confirmatory study with synthetic peptides showed that valine–alanine (VA), valine–leucine (VL), tryptophan–leucine (WL) and tryptophan–isoleucine (WI) displayed DPP-IV IC50 values < 170 μM. The NF and LC–MS strategies employed herein represent a new approach for the targeted identification of short peptides within bioactive food protein hydrolysates.