title: Release of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from milk protein isolate (MPI) during enzymatic hydrolysis.
abstract: The release of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from bovine milk protein isolate (MPI) during trypsin hydrolysis was studied using a design of experiments (DOE) approach. A 3 factor×3 level DOE including temperature (40, 50 and 60°C), enzyme to substrate ratio (E:S; 0.50, 1.25 and 2.00% (w/w)) and hydrolysis time (60, 150 and 240min) was used during the generation of 15 hydrolysates (H1-H15). The degree of hydrolysis (DH) varied between 6.98±0.31 (H8) to 12.75±0.62% (H10). The DPP-IV half maximal inhibitory concentration (IC50) ranged from 0.68±0.06 (H11)/0.68±0.10 (H4) to 1.59±0.11mgmL-1(H8). Temperature had no effect (p>0.05) on the DPP-IV IC50value, while an increase in E:S or time significantly decreased DPP-IV IC50value (p<0.05). The DPP-IV IC50value of 0.69mgmL-1, predicted by response surface methodology (RSM), to be obtained with an hydrolysate generated at 50.5°C, 2% ES and 231min (H16) was similar to the experimentally obtained value (DPP-IV IC50=0.66±0.10mgmL-1, p>0.05, n=3). Following simulated gastrointestinal digestion (SGID) of H16 (H16_CorPP), the DPP-IV IC50value increased (p<0.05) to 0.90±0.07mgmL-1. There was no significant difference between the DPP-IV IC50value of the SGID of MPI (MPI_CorPP, 0.89±0.11mgmL-1) and that of H16_CorPP. Potent known DPP-IV inhibitory peptide sequences were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) within H16, some of which were also present within H16_CorPP. MPI hydrolysates may be of interest for serum glucose regulation in humans.
authors.affiliation: Department of Biological Sciences, University of Limerick, Limerick, Ireland; Food for Health Ireland (FHI), University of Limerick, Limerick, Ireland.
authors.forename: Alice B
authors.initials: AB
authors.lastname: Nongonierma
authors.affiliation: Department of Biological Sciences, University of Limerick, Limerick, Ireland.
authors.forename: Caterina
authors.initials: C
authors.lastname: Mazzocchi
authors.affiliation: Department of Biological Sciences, University of Limerick, Limerick, Ireland; Food for Health Ireland (FHI), University of Limerick, Limerick, Ireland.
authors.forename: Sara
authors.initials: S
authors.lastname: Paolella
authors.affiliation: Department of Biological Sciences, University of Limerick, Limerick, Ireland; Food for Health Ireland (FHI), University of Limerick, Limerick, Ireland. Electronic address: dick.fitzgerald@ul.ie.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: FitzGerald
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002853:Chromatography, Liquid; D004063:Digestion; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D054873:Dipeptidyl-Peptidase IV Inhibitors / Q000032:analysis*; D006801:Humans; D006868:Hydrolysis; D008894:Milk Proteins / Q000378:metabolism*; D010455:Peptides / Q000032:analysis*; D011492:Protein Hydrolysates / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D014357:Trypsin / Q000378:metabolism*
chemical_list: D054873:Dipeptidyl-Peptidase IV Inhibitors; D008894:Milk Proteins; D010455:Peptides; D011492:Protein Hydrolysates; D018819:Dipeptidyl Peptidase 4; D014357:Trypsin
keywords: Bioactive peptides; Dipeptidyl peptidase IV inhibition; Milk protein isolate; Response surface methodology; Trypsin