In vitro evaluation of digestive and endolysosomal enzymes to cleave CML-modified Ara h 1 peptides.
Ara h 1 is a major peanut allergen. Processing-induced modifications may modulate the allergenic potency of Ara h 1. Carboxymethyl lysine (CML) modifications are a commonly described nonenzymatic modification on food proteins. In the current study, we tested the ability of digestive and endolysosomal proteases to cleave CML-modified and unmodified Ara h 1 peptides. Mass spectrometric analyses of the digested peptides demonstrate that carboxymethylation of lysine residues renders these peptides refractory to trypsin digestion. We did not detect observable differences in the simulated gastric fluid or endolysosomal digestion between the parental and CML-modified peptides. One of the tested peptides contains a lysine residue previously shown to be CML modified laying in a previously mapped linear IgE epitope, but we did not observe a difference in IgE binding between the modified and parental peptides. Our findings suggest a molecular mechanism for the increased resistance of peanut allergens modified by thermal processing, such as Ara h 1, to digestion in intestinal fluid after heating and could help explain how food processing-induced modifications may lead to more potent food allergens by acting to protect intact IgE epitopes from digestion by proteases targeting lysine residues.
United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124.
Christopher P
CP
Mattison
Ragon Institute of MGH, MIT and Harvard 400 Technology Square, Cambridge, Massachusetts, 02139 ; Harvard Medical School Boston, Massachusetts.
Jens
J
Dinter
Ragon Institute of MGH, MIT and Harvard 400 Technology Square, Cambridge, Massachusetts, 02139.
Matthew J
MJ
Berberich
United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124.
Si-Yin
SY
Chung
United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124.
Shawndrika S
SS
Reed
Ragon Institute of MGH, MIT and Harvard 400 Technology Square, Cambridge, Massachusetts, 02139 ; Harvard Medical School Boston, Massachusetts.
Sylvie
S
Le Gall
United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124.
Casey C
CC
Grimm
Ara h 1; Maillard reaction; carboxymethyl lysine; mass spectrometry; peptide; proteolysis