Composition, secondary structure, and self-assembly of oat protein isolate

Gang Liu, Ji Li, Ke Shi, Su Wang, Jiwang Chen, Ying Liu, Qingrong Huang

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48 Scopus citations


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% β-tum, 19% α-helix, and 74% β-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.

Original languageEnglish (US)
Pages (from-to)4552-4558
Number of pages7
JournalJournal of agricultural and food chemistry
Issue number11
StatePublished - Jun 10 2009

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)


  • Amino acid composition
  • Atomic force microscopy
  • FTIR
  • Oat protein isolate
  • Secondary structure

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