Compositional and conformational analysis of yam proteins by near infrared fourier transform Raman spectroscopy.
Fourier transform (FT)-Raman spectroscopy was employed to study the molecular structure of yam proteins isolated from three commonly consumed yam species including Dioscorea alata L., D. alata L. var. purpurea, and Dioscorea japonica. Although D. alata L. and D. alata L. var. purpurea consisted of similar amino acid residues, they still exhibited significant differences in conformational arrangement. The secondary structure of D. alata L. was mainly an alpha-helix, while D. alata L. var. purpurea was mostly in antiparallel beta-sheets. In contrast, D. japonica, which belongs to a different species, exhibited explicit differences in amino acid compositions and molecular structures of which the conformation was a mixed form of alpha-helices and antiparallel beta-sheets. FT-Raman directly proved the existence of S-S in yam proteins, implying that oligomer formation in yam proteins might be due to disulfide linking of dioscorin (32 kDa). The microenvironment of aromatic amino acids and the state of S-S in yam proteins were also discussed.
Liao
Yu-Hsiu
YH
Department of Food Science, National Chiayi University, 300 University Road, Chiayi, 60083, Taiwan.
Wang
Chih-Hsien
CH
Tseng
Chin-Yin
CY
Chen
Hsiu-Ling
HL
Lin
Long-Liu
LL
Chen
Wenlung
W
D000596:Amino Acids / Q000032:analysis; D027742:Dioscorea / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
D000596:Amino Acids; D010940:Plant Proteins