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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Bioproducts Research » Research » Publications at this Location » Publication #322586

Research Project: Domestic Production of Natural Rubber and Industrial Seed Oils

Location: Bioproducts Research

Title: Analysis of castor by ELISAs that distinguish Ricin and Ricinus communis agglutinin (RCA)

item Brandon, David
item McKeon, Thomas
item Patfield, Stephanie
item He, Xiaohua

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2015
Publication Date: 12/24/2016
Citation: Brandon, D.L., McKeon, T.A., Patfield, S.A., He, X. 2016. Analysis of castor by ELISAs that distinguish Ricin and Ricinus communis agglutinin (RCA). Journal of the American Oil Chemists' Society. 93:359-363.

Interpretive Summary: Castor oil is used for lubricants, detergents, polymers, plastics and solvents, but the US relies on imported castor oil and petroleum as the basis of most of these products. The presence of ricin in the castor seed is a major impediment to re-introducing castor as a crop that can produce the equivalent of up to 6 barrels of oil per acre under ideal conditions, and is suited for growth on marginal and set-aside land. This study evaluated antibody-based methods for measuring the content of 2 closely related, toxic castor seed (bean) proteins. Monoclonal antibodies were able to distinguish between the two proteins, ricin and Ricinus communis agglutinin. This methodology could help identify a low-ricin or ricin-free castor variety for a profitable crop that requires low agricultural input and provides greater safety to agricultural workers and the public.

Technical Abstract: To facilitate the analysis of castor (Ricinus communis L.) seed fractions and germplasm for ricin content, we investigated the use of enzyme-linked immunosorbent assay (ELISA) methods to differentiate between ricin toxin and the related Ricinus communis agglutinin (RCA). Both proteins are based on a heterodimeric AB structure, with a common A-chain. RCA comprises two dimers of A- and B-chains. The two proteins are found in the meal remaining after castor oil extraction and impede the commercial production of castor seed in the United States. We identified pairs of monoclonal antibodies (mAbs) that could distinguish between these structurally related proteins that share a common A-chain. Antibody specificity was determined by ELISA and checked by immunoblotting.We found that mAb-mAb pairs provide good discrimination between the castor proteins, but that a mAb paired with a commercial polyclonal antibody (pAb) provided good, indiscriminate detection of both.