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Molecular characterization of alpha-lactalbumin folding variants that induce apoptosis in tumor cells

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Author

Summary, in English

This study characterized a protein complex in human milk that induces apoptosis in tumor cells but spares healthy cells. The active fraction was purified from casein by anion exchange chromatography. Unlike other casein components the active fraction was retained by the ion exchanger and eluted after a high salt gradient. The active fraction showed N-terminal amino acid sequence identity with human milk alpha-lactalbumin and mass spectrometry ruled out post-translational modifications. Size exclusion chromatography resolved monomers and oligomers of alpha-lactalbumin that were characterized using UV absorbance, fluorescence, and circular dichroism spectroscopy. The high molecular weight oligomers were kinetically stable against dissociation into monomers and were found to have an essentially retained secondary structure but a less well organized tertiary structure. Comparison with native monomeric and molten globule alpha-lactalbumin showed that the active fraction contains oligomers of alpha-lactalbumin that have undergone a conformational switch toward a molten globule-like state. Oligomerization appears to conserve alpha-lactalbumin in a state with molten globule-like properties at physiological conditions. The results suggest differences in biological properties between folding variants of alpha-lactalbumin.

Publishing year

1999-03-05

Language

English

Pages

96-6388

Publication/Series

Journal of Biological Chemistry

Volume

274

Issue

10

Document type

Journal article

Publisher

American Society for Biochemistry and Molecular Biology

Topic

  • Biochemistry and Molecular Biology

Keywords

  • Amino Acid Sequence
  • Apoptosis
  • Dimerization
  • Female
  • Humans
  • Lactalbumin
  • Milk, Human
  • Molecular Sequence Data
  • Neoplasms
  • Protein Folding
  • Structure-Activity Relationship

Status

Published

Research group

  • Experimental Infection Medicine, Malmö

ISBN/ISSN/Other

  • ISSN: 0021-9258