Abstract
The seeds of Jatropha curcas (jatropha), which contain 27-40% oil, are an important source for bio-diesel production. For making bio-diesel production profitable, it is desirable to use the seed meal generated as a byproduct for producing animal feed. Although jatropha seed meal contains 50-62% protein, it is not suitable as an animal feed without additional processing because one of the seed meal proteins, curcin, is a toxin that inhibits protein synthesis. A rapid detection method of curcin will be useful in determining any remnant of the toxin in processed jatropha seed products. The objective of this research was to develop an immunological method to quantify curcin in jatropha, especially in the seed meal. Jatropha contains two types of curcin, curcin-L and curcin, which have 89% similarity with each other at amino acid level. The cDNA for curcin-L was isolated from a jatropha cDNA library and sequenced. The codon-optimized full-length curcin-L cDNA and a truncated derivative were cloned and expressed in E. coli. The purified protein obtained by expressing the truncated cDNA was used to develop polyclonal antibody (anti-curcin-L) in rabbit. Anti-curcin-L could detect both curcin-L and curcin even at 1:10,000 dilutions. The two curcins were detected in all parts of jatropha including leaf, cotyledonary leaf, stem and root. We also detected and quantified total curcin (curcin-L and curcin) from two different seed meal samples, using anti-curcin-L and densitometry. This method will be useful in rapid detection and quantification of total curcin present in any commercial feed containing jatropha seed meal.
Keywords: Antibody, bio-diesel, curcin, immunodetection, Jatropha curcas, toxin, meal, protein, seeds, leaf.
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