Molecular cloning, mass spectrometric identification, and nutritional evaluation of 10 coixins in adlay ( Coix lachryma-jobi L.).
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.
Lin
Li-Jen
LJ
School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan.
Hsiao
Eric S L
ES
Tseng
Hsen-Shong
HS
Chung
Mei-Chu
MC
Chua
Anna C N
AC
Kuo
Ming-En
ME
Tzen
Jason T C
JT
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
D000596:Amino Acids; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; C072398:alpha-coixin protein, Coix lacryma-jobi