Comprehensive amino acid composition analysis of seed storage proteins of cereals and legumes: identification and understanding of intrinsically disordered and allergenic peptides

Abstract

The seed storage proteins of cereal and legumes are the primary source of amino acids which are required for sustaining the nitrogen and carbon demands during germination and growth. Humans derive most of their dietary proteins from storage proteins in form of a wide variety of foods, for consumption. The amino acid content of most of these proteins is biased and the need for this biasness is not understood. The high abundance of proline, glutamine, and cysteine in cereals makes the gluten fraction viscoelastic. The cereal proteins have less charge and legume proteins have more charge on them. Their non-polar amino acid distribution has large variations. These characteristics are strongly responsible for the partial and complete unfolding of several domains of the storage proteins. Many of the storage proteins share a highly conserved structural feature within the cupin superfamily spread across all kingdoms of life. The intrinsically disordered viscoelastic proteins help in making dough which is vital for the quality of bread. Unfolded regions harbor more immunogenic sequences and cause food-related allergies and intolerance. We have discussed these properties in terms of comparison of cereal and legume storage protein sequences and allergy. Our study supports the findings that large disordered regions contain allergen-representative peptides. Interestingly, a high number of allergen-representative peptides were cleavable by digestive enzymes. Furthermore, unfolded storage proteins mimic microbial immunogens to induce a memory immune response. Results findings can be used to guide the understanding of immunological characteristics of storage proteins and may assist in treatment decisions for food allergy.

Communicated by Ramaswamy H. Sarma

Keywords:

• Seed storage protein
• intrinsically disordered
• amino acids
• allergenic peptides
• cereal
• legume

Acknowledgements

We would like to acknowledge Dr. A. Srinivasan, Ex-Professor, Department of Biophysics, AIIMS, Delhi for initial intellectual assistance for this study.

Data availability statement

The data supporting the findings of this manuscript are available within the paper and its supplementary files. Additional data will be made available from the corresponding author upon reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

We would like to acknowledge the fellowship grant from Department of Health Research, Ministry of Health & Family Welfare (R.12013/07/2019-HR) to PS at the time of writing this manuscript. However, no any funding has been received for conducting, writing, and publication of this work.