Insights into proteolytic processing of the major peanut allergen Ara h 2 by endogenous peanut proteases.
BACKGROUND
The major peanut allergens are Ara h 1, Ara h 2 and Ara h 6. Proteolytic processing has been shown to be required for the maturation process of Ara h 6. The aim of this study was to examine whether Ara h 2 undergoes proteolytic processing and, if so, whether proteolytic processing influences its ability to bind human immunoglobulin E (IgE).


RESULTS
Ara h 2 isolated from peanut extract under conditions of protease inhibition revealed a single additional peak for its two known isoforms (Ara h 2.01 and Ara h 2.02), corresponding to a C-terminally truncated form lacking a dipeptide (RY). Ara h 2 isolated in the absence of protease inhibition, however, yielded two additional peaks, identified as C-terminally truncated forms lacking either a dipeptide (RY) or a single tyrosine residue. The IgE-binding capacity of the Ara h 2 truncated forms was not altered.


CONCLUSIONS
Ara h 2 undergoes proteolytic processing by peanut proteases that involves C-terminal removal of a dipeptide. Hence Ara h 2 isolated from peanut extract is a complex mixture of two isoforms expressed by different genes, Ara h 2.01 and Ara h 2.02, as well as truncated forms generated by the proteolytic processing of these isoforms.
Radosavljevic
Jelena
J
Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski Trg 12-16, Belgrade, Serbia. radosavljevic@chem.bg.ac.rs
Dobrijevic
Dragana
D
Jadranin
Milka
M
Blanusa
Milan
M
Vukmirica
Jelena
J
Cirkovic Velickovic
Tanja
T
D055516:2S Albumins, Plant / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000485:Allergens / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D052179:Antigens, Plant / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010367:Arachis / Q000737:chemistry*; D004151:Dipeptides; D006023:Glycoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006868:Hydrolysis; D007073:Immunoglobulin E; D007536:Isomerism; D010447:Peptide Hydrolases / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D014443:Tyrosine
D055516:2S Albumins, Plant; D000485:Allergens; D052179:Antigens, Plant; C500890:Ara h 2 allergen, Arachis hypogaea; D004151:Dipeptides; D006023:Glycoproteins; D010936:Plant Extracts; D010940:Plant Proteins; D007073:Immunoglobulin E; D014443:Tyrosine; D010447:Peptide Hydrolases