Adsa Logo White Adsa Title White

Liquid chromatography-tandem mass spectrometry analysis of glycomacropeptide from whey protein isolate.

Y. Qu

Events

06-22-2020

Join Y. Qu on this page for a live text chat!
6:00 PM - 8:00 PM GMT

Abstract:

M46
Liquid chromatography-tandem mass spectrometry analysis of glycomacropeptide from whey protein isolate.
Y. Qu*, B. J. Kim, D. Dallas. Oregon State University Corvallis, OR.

κ-Casein glycomacropeptide (GMP), a 64-amino-acid peptide, is released from κ-casein after rennet treatment and is one of the major peptides in whey protein isolate (WPI). GMP has anti-inflammatory and antibacterial actions. GMP has 2 major amino acid sequences and many different modifications including glycosylation, phosphorylation and oxidation, yet no previous work has provided a comprehensive profile of all the different distinct GMP forms present in whey. The full characterization of the composition and structure of GMP is important to help to understand the bioactivity of GMP. We therefore aimed to develop an analytical method to profile GMP and GMP peptide fragments in WPI using Orbitrap mass spectrometry combined with a nano-liquid chromatography (LC). A commercial WPI was dissolved in water and purified by C18-solid-phase extraction and characterized by a nano-LC/Orbitrap MS/MS under electron-transfer/higher-energy collision dissociation mode. MS and MS/MS results were interpreted using Byos (Byonic and Byologic) processing and manual spectral inspection to verify structures. Forty-five distinct intact GMP forms were identified in the WPI. One intact GMP was without any modification, 5 intact GMP forms were glycosylated only, 4 were phosphorylated only, one was oxidized only, 3 were both phosphorylated and oxidized, 22 were for both glycosylated and phosphorylated and 8 were glycosylated, phosphorylated and oxidized. Four O-linked glycosylations (HexNAc1Hex1, HexNAc1Hex1NeuAc1, HexNAc1Hex1NeuAc1, HexNAc1Hex1NeuAc2) were present on the GMP. In addition to intact GMP, 186 distinct GMP-derived peptides were identified in the WPI, likely generated from partial hydrolysis during whey processing or storage. These glycopeptides were between 9 and 63 amino acid length. We have demonstrated the efficacy of this novel analytical approach to comprehensively profile the range of GMP and GMP-derived structures in whey protein isolates. Our comprehensive profile of all the different distinct GMP forms present in whey provides some fundamental information on determining how GMP is digested in human and understanding the bioactivity of GMP.

Keywords: glycomacropeptide, LC-MS/MS, whey.

Biography: I am a second-year master's student at Oregon State University. I worked as a faculty research assistant in Dr. David Dallas's lab at the Oregon State University for two years after graduating from the University of California, Davis with a Food Science Bachelor of Science degree in 2016. I have been performing research on isolating specific bioactive peptides from human and bovine milk since 2015. My master's program focuses on examining the digestion, absorption and antimicrobial and immunomodulatory actions of kappa-casein glycomacropeptide in healthy adults. Earning my Master's degree in Food Science at OSU will enable me to enter into a career in the dairy industry where I can translate my experiences into new food developments for optimizing human health through dairy products.