Identification of the Critical Amino Acid Residues of Immunoglobulin E and Immunoglobulin G Epitopes in α-Lactalbumin by Alanine Scanning Analysis

J Food Sci. 2016 Oct;81(10):T2597-T2603. doi: 10.1111/1750-3841.13425. Epub 2016 Sep 7.

Abstract

α-Lactalbumin represents one of the major allergens causing cow milk allergy. Few studies have clearly evaluated immunological relationships between immunoglobulin E (IgE) and immunoglobulin G (IgG)-binding epitopes of α-lactalbumin. IgE- and IgG-binding epitopes were immunolabeled with individual sera from cow milk-allergic patients. Alanine scanning of immunodominant epitopes was used to identify the critical amino acid (aa). Our initial data revealed Val8 , Phe9 , Arg10 , Tyr103 , Leu105 , and His107 were the critical aa for IgE-binding epitope. The critical aa of IgG-binding epitopes were Phe9 , Leu15 , Pro24 , Trp26 , and His32 . This study will provide necessary information to alter the cDNA to encode a protein capable of activating milk-specific T cells, but with reduced IgE- or IgG-binding capacity.

Keywords: cow milk allergy; critical amino acid; epitope; α-lactalbumin.

MeSH terms

  • Alanine / chemistry*
  • Allergens / immunology
  • Amino Acid Sequence
  • Animals
  • Caseins / chemistry
  • Cattle
  • Child, Preschool
  • DNA, Complementary / metabolism
  • Epitopes / immunology*
  • Humans
  • Immunoglobulin E / immunology*
  • Immunoglobulin G / immunology*
  • Infant
  • Lactalbumin / chemistry*
  • Milk / immunology
  • Milk Hypersensitivity / immunology*
  • Peptides / chemistry
  • Protein Binding
  • Protein Conformation
  • Signal Transduction

Substances

  • Allergens
  • Caseins
  • DNA, Complementary
  • Epitopes
  • Immunoglobulin G
  • Peptides
  • Immunoglobulin E
  • Lactalbumin
  • Alanine