Probing novel allergenic proteins of commonly consumed legumes

Abstract

Leguminous crops are the main source of protein in Asian subcontinent including India and their proteins may induce allergic reactions in sensitized individuals. Pepsin resistance of proteins is a characteristic feature of most of the allergens. Simulated gastric fluid (SGF) assay as validated by digestion of purified known allergenic and non-allergenic proteins was the basis of this study. Purified allergenic proteins were stable to SGF digestion contrary to rapidly digested non-allergenic proteins. Crude proteins extracts (CPE) of soybean, peanut, chickpea, black gram, kidney bean and Bengal gram were digested in vitro to detect their non-digestible proteins. Six proteins from soybean and seven from peanut remained undigested after SGF digestion. Likewise, seven proteins from chickpea (70, 64, 55, 45, 35, 20 and 18 kDa), ten from black gram (47, 30, 29, 28, 26, 24, 22, 16, 14 and 12 kDa), five from kidney bean (45, 29, 24, 20 and 6.5 kDa) and one from Bengal gram (20 kDa) remained undigested in SGF. Most of the proteins stable in SGF for more than 2 min showed similarity with characterized allergens on the basis of their molecular weights as in case of soybean, peanut, chickpea and black gram. Also, soybean and chickpea stable proteins showed IgE binding property with respective allergic patient’s sera. The non-digestible proteins from the chickpea, black gram, kidney bean and Bengal gram are being reported for the first time by our group. IgE binding of SGF resistant soybean and chickpea proteins is being reported first time as well.

Keywords::

• Bengal gram
• kidney bean
• legume allergy
• pepsin resistant proteins
• simulated gastric fluid

Acknowledgments

We are grateful to the Director of the Institute for his keen interest in this study. Thanks are due to Network Project COR-0017 and the Supra Institutional Project-08 (SIP-08) of the Council of Scientific and Industrial Research (CSIR), New Delhi, for financial support.

Amita Misra thanks the Indian Council of Medical Research (ICMR), New Delhi, for the award of Senior Research Fellowship. The authors thank Mr. B. D. Bhattacharji for help in editing of the manuscript. Thanks are also due to Dr. D. N. Kachru, Scientist, Indian Institute of Toxicology Research, for providing purified Cry1Aa and Cry1 Ab proteins. The IITR manuscript no. of this article is 2623.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.