Physicochemical and functional properties of a protein isolate from maca (Lepidium meyenii) and the secondary structure and immunomodulatory activity of its major protein component

Food Funct. 2019 May 22;10(5):2894-2905. doi: 10.1039/c8fo02490a.

Abstract

Maca protein isolate (MPI) was extracted from maca root, and its physicochemical and functional properties, and the secondary structure and immunomodulatory activity of its major protein component, MMP, were investigated. The MPI lacked essential amino acids compared with soybean protein isolate (SPI) and casein, but was rich in cysteine and proline. The MPI had rich free sulfhydryl (20.6 μmol g-1), and its surface hydrophobicity (H0, 812.4), oil absorption capacity (7.4 g g-1), foaming capacity (100%) and emulsifying activity (58.2 m2 g-1) were higher than that of SPI. However, the thermal stability (Td, 87.4 °C), foaming stability (75%) and emulsifying stability (26.3 min) of the MPI were weaker than that of the SPI. MMP was a pentamer with a molecular weight of 22 kDa and rich in β-sheets. MMP could significantly enhance the phagocytic capacity and promote the NO, TNF-α and IL-6 secretion of RAW 264.7 cells, involving toll-like receptor 4 and complement receptor 3 mainly.

MeSH terms

  • Animals
  • Hydrophobic and Hydrophilic Interactions
  • Immunologic Factors / chemistry*
  • Immunologic Factors / pharmacology
  • Interleukin-6 / genetics
  • Interleukin-6 / immunology
  • Lepidium / chemistry*
  • Macrophages / drug effects
  • Macrophages / immunology
  • Mice
  • Molecular Weight
  • Plant Proteins / chemistry*
  • Plant Proteins / isolation & purification
  • Plant Proteins / pharmacology
  • Protein Structure, Secondary
  • RAW 264.7 Cells
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / immunology
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / immunology

Substances

  • Immunologic Factors
  • Interleukin-6
  • Plant Proteins
  • Toll-Like Receptor 4
  • Tumor Necrosis Factor-alpha