title: Molecular cloning, mass spectrometric identification, and nutritional evaluation of 10 coixins in adlay ( Coix lachryma-jobi L.).
abstract: 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 alpha-coixin isoforms, 1 delta-coixin, and 1 gamma-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 alpha-coixin isoforms, 13.3% in delta-coixin, and 31.2% in gamma-coixin). The 8 alpha-coixin isoforms are low in methionine, cysteine, and lysine (on average, 0.8, 0.6, and 0.1%, respectively). However, the delta-coixin is a sulfur-rich protein (18.2% methionine and 9.1% cysteine), and the gamma-coixin is a nutritive protein composed of 2.0% methionine, 6.6% cysteine, 2.6% lysine, and 8.9% histidine. The company of delta-coixin and gamma-coixin with alpha-coixin isoforms enhances the nutritional value of alday grain for human consumption.
authors.affiliation: School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Lin
authors.forename: Eric S L
authors.initials: ES
authors.lastname: Hsiao
authors.forename: Hsen-Shong
authors.initials: HS
authors.lastname: Tseng
authors.forename: Mei-Chu
authors.initials: MC
authors.lastname: Chung
authors.forename: Anna C N
authors.initials: AC
authors.lastname: Chua
authors.forename: Ming-En
authors.initials: ME
authors.lastname: Kuo
authors.forename: Jason T C
authors.initials: JT
authors.lastname: Tzen
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D003001:Cloning, Molecular; D031742:Coix / Q000737:chemistry*; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000032:analysis / Q000235:genetics; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009753:Nutritive Value; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012639:Seeds / Q000737:chemistry; D016415:Sequence Alignment
chemical_list: D000596:Amino Acids; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; C072398:alpha-coixin protein, Coix lacryma-jobi