Characterization of lactosylated proteins of infant formula powders using two-dimensional gel electrophoresis and nanoelectrospray mass spectrometry

Electrophoresis. 2002 Aug;23(15):2505-12. doi: 10.1002/1522-2683(200208)23:15<2505::AID-ELPS2505>3.0.CO;2-M.

Abstract

Infant formula powders were analyzed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) to assess the whey proteins quality, which may be altered by the heat treatment used during the processing conditions. Lactosylation was found to be the major chemical modification occurring in whey proteins. In parallel, a two-dimensional (2-D) gel electrophoresis was performed on the milk sample and the entire protein patterns were analyzed by nano-ESI-MS after cutting the different gel spots and in-gel trypsin digestion. A highly selective and specific tandem MS technique has been developed to characterize and localize up to ten lactosylation sites in beta-lactoglobulin (beta-Lg) and alpha(S2)-casein. alpha-Lactalbumin (alpha-La), with five lactosylated peptides, was found to be an interesting protein marker in the milk powder sample to detect chemical modification induced by the processing/storage conditions.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Caseins / chemistry
  • Electrophoresis, Gel, Two-Dimensional / methods*
  • Humans
  • Infant
  • Infant Food / analysis*
  • Lactalbumin / chemistry
  • Lactoglobulins / chemistry
  • Lactose / chemistry*
  • Milk Proteins / chemistry*
  • Nanotechnology
  • Powders
  • Spectrometry, Mass, Electrospray Ionization / methods*
  • Whey Proteins

Substances

  • Caseins
  • Lactoglobulins
  • Milk Proteins
  • Powders
  • Whey Proteins
  • Lactalbumin
  • Lactose