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Molecular Cloning, Mass Spectrometric Identification, and Nutritional Evaluation of 10 Coixins in Adlay (Coix lachryma-jobi L.)

Lin, Li-Jen, Hsiao, Eric S.L., Tseng, Hsen-Shong, Chung, Mei-Chu, Chua, Anna C.N., Kuo, Ming-En, Tzen, Jason T.C.
Journal of agricultural and food chemistry 2009 v.57 no.22 pp. 10916–10921
molecular cloning, mass spectrometry, nutrient content, nutritive value, Coix lacryma-jobi, herbal medicines, medicinal plants
Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is regarded as a nutritive food source as well as herbal medicine. The food nutrition is a consequence of its high protein content and superior amino acid composition. From ca. 200 expressed sequence tag (EST) sequences in maturing adlay grains, clones encoding precursor polypeptides of 10 seed storage proteins in the prolamin family, including 8 α-coixin isoforms, 1 δ-coixin, and 1 γ-coixin, were identified. Full-length cDNA fragments encoding these 10 coixins were obtained by PCR cloning. Mass spectrometric analyses confirmed the presence of these 10 coixins in the extract of adlay grain. Calculated amino acid compositions indicate that all 10 coixins are rich in glutamine (>20% in α-coixin isoforms, 13.3% in δ-coixin, and 31.2% in γ-coixin). The 8 α-coixin isoforms are low in methionine, cysteine, and lysine (on average, 0.8, 0.6, and 0.1%, respectively). However, the δ-coixin is a sulfur-rich protein (18.2% methionine and 9.1% cysteine), and the γ-coixin is a nutritive protein composed of 2.0% methionine, 6.6% cysteine, 2.6% lysine, and 8.9% histidine. The company of δ-coixin and γ-coixin with α-coixin isoforms enhances the nutritional value of alday grain for human consumption.