Proteomic Profiling of Major Peanut Allergens and Their Post-Translational Modifications Affected by Roasting

Abstract

Post-translational modifications (PTMs) are covalent changes occurring on amino acid side chains of proteins and yet are neglected structural and functional aspects of protein architecture. The objective was to detect differences in PTM profiles that take place after roasting using open PTM search. We conducted a bottom-up proteomic study to investigate the impact of peanut roasting on readily soluble allergens and their PTM profiles. Proteomic PTM profiling of certain modifications was confirmed by Western blotting with a series of PTM-specific antibodies. In addition to inducing protein aggregation and denaturation, roasting may facilitate change in their PTM pattern and relative profiling. We have shown that Ara h 1 is the most modified major allergen in both samples in terms of modification versatility and extent. The most frequent PTM was methionine oxidation, especially in roasted samples. PTMs uniquely found in roasted samples were hydroxylation (Trp), formylation (Arg/Lys), and oxidation or hydroxylation (Asn). Raw and roasted peanut extracts did not differ in the binding of IgE from the serum of peanut-sensitised individuals done by ELISA. This study provides a better understanding of how roasting impacts the PTM profile of major peanut allergens and provides a good foundation for further exploration of PTMs.

Peanut Allergenicity: An Insight into Its Mitigation Using Thermomechanical Processing

“…The total extractable allergen content decreased from 71% in raw peanuts to 21% in roasted peanuts [ 58 ]. Recently, Ðukić and collaborators investigated the post-translational modifications (PTMs) of peanut proteins as affected by roasting [ 64 ]. The most common PTMs observed were oxidation (met), formylation (Arg/Lys), hydroxylation (Trp), and oxidation or hydroxylation (Asn).…”

Antioxidant Properties of Protein-Rich Plant Foods in Gastrointestinal Digestion—Peanuts as Our Antioxidant Friend or Foe in Allergies

“…There are 62 distinct families of peanut proteins spread into 140 different, non-redundant protein groups (Table 1), with more than 500 iso-and proteoforms, as determined by high-resolution 2D SDS-PAGE [37]. Table 1 can be used to estimate the change in antioxidant potential due to the release of peptides under the action of pepsin, trypsin and chymotrypsin, taking into account available data [18,19,36], in silico digestion scenarios and already known properties of small peptides conferring antioxidant properties. If not otherwise noted, qualitative data are extracted from the Supplementary tables of Hebling et al, 2012 [36] (e.g., all empty, merged cells of relative abundance without a specific reference).…”

“…Moreover, roasting resulted in a general enrichment of the major peanut allergens (23.2%) due to the double extent of Ara h 3, whereas the minor allergens practically disappeared in the roasted preparation (Figure 1B). [18]. (A) Label-free quantification of raw and roasted peanut allergens determined using PEAKS X Pro Studio (two groups, each with biological triplicates).…”

“…This, in turn, may increase antioxidative power, correlating with the intensity of thermal treatment and the extent of Maillard products formed, as in the case of spray-dried camel milk [ 17 ]. In addition, thermal processing may alter the protein profile, including the associated modification profile [ 18 ] and/or the amount of food molecules extracted into the liquid phase of gastrointestinal digestion, directly affecting allergenicity [ 19 ] and, very likely, altering antioxidant potential.…”

“…Figure1. Raw and roasted PBS-based peanut extract protein profiles were calculated from Report S2, supplementary material[18]. (A) Label-free quantification of raw and roasted peanut allergens determined using PEAKS X Pro Studio (two groups, each with biological triplicates).…”