Composition, secondary structure, and self-assembly of oat protein isolate.
The amino acid compositions, secondary structure, and self-assembly of oat protein isolate (OPI), which was purified from the high-protein Chinese oat, have been investigated by using a combination of amino acid analysis, Fourier transform infrared spectroscopy (FTIR), and tapping mode atomic force microscopy (TP-AFM). OPI, with molecular weights ranging from 14.0 kDa to 66.0 kDa, was rich in essential amino acids and contained 24.7% glutamic acid and 8.1% leucine. The amino acid contents of OPI are 4.5-8.7 times higher than those of oat flour. The secondary structures of OPI have been quantified by the deconvolution of the amide I band of the FTIR spectrum of OPI, which were found to contain approximately 7% beta-turn, 19% alpha-helix, and 74% beta-sheet. Tapping mode AFM results further suggest that the oat protein isolate has two major types of shapes, ellipsoidal and disk-like. At protein concentrations below 0.5 mg/mL, most of the OPI molecules are in the isolated form. However, when the concentration of OPI reaches 1.0 mg/mL, some of the OPI molecules self-assembled into large and heterogeneous protein aggregates.
Liu
Gang
G
School of Light Chemistry and Food Science, South China University of Technology, Guangzhou, Guangdong Province, PR China.
Li
Ji
J
Shi
Ke
K
Wang
Su
S
Chen
Jiwang
J
Liu
Ying
Y
Huang
Qingrong
Q
D000596:Amino Acids / Q000032:analysis; D018554:Avena / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D010936:Plant Extracts / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
D000596:Amino Acids; D010936:Plant Extracts; D010940:Plant Proteins