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Bovine lactoferrin binds oleic acid to form an anti-tumor complex similar to HAMLET
- Source :
- Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids. (4):535-543
- Publisher :
- The Authors. Published by Elsevier B.V.
-
Abstract
- α-Lactalbumin (α-LA) can bind oleic acid (OA) to form HAMLET-like complexes, which exhibited highly selective anti-tumor activity in vitro and in vivo. Considering the structural similarity to α-LA, we conjectured that lactoferrin (LF) could also bind OA to obtain a complex with anti-tumor activity. In this study, LF–OA was prepared and its activity and structural changes were compared with α-LA–OA. The anti-tumor activity was evaluated by methylene blue assay, while the apoptosis mechanism was analyzed using flow cytometry and Western blot. Structural changes of LF–OA were measured by fluorescence spectroscopy and circular dichroism. The interactions of OA with LF and α-LA were evaluated by isothermal titration calorimetry (ITC). LF–OA was obtained by heat-treatment at pH 8.0 with LD50 of 4.88, 4.95 and 4.62 μM for HepG2, HT29, and MCF-7 cells, respectively, all of which were 10 times higher than those of α-LA–OA. Similar to HAMLET, LF–OA induced apoptosis in tumor cells through both death receptor- and mitochondrial-mediated pathways. Exposure of tryptophan residues and the hydrophobic regions as well as the loss of tertiary structure were observed in LF–OA. Besides these similarities, LF showed different secondary structure changes when compared with α-LA, with a decrease of α-helix and β-turn and an increase of β-sheet and random coil. ITC results showed that there was a higher binding number of OA to LF than to α-LA, while both of the proteins interacted with OA through van der Waals forces and hydrogen bonds. This study provides a theoretical basis for further exploration of protein–OA complexes.
- Subjects :
- Circular dichroism
Oleic Acids
Apoptosis
Protein Structure, Secondary
Anti-tumor
chemistry.chemical_compound
Western blot
Neoplasms
medicine
Animals
Humans
Molecular Biology
Protein secondary structure
biology
medicine.diagnostic_test
Lactoferrin
Circular Dichroism
Tryptophan
Hydrogen Bonding
Isothermal titration calorimetry
Hep G2 Cells
Cell Biology
Flow Cytometry
Oleic acid
Protein tertiary structure
chemistry
Biochemistry
Lactalbumin
biology.protein
Cattle
HAMLET (protein complex)
HAMLET
Subjects
Details
- Language :
- English
- ISSN :
- 13881981
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids
- Accession number :
- edsair.doi.dedup.....f25ce187baab76499ff30ad67c57506b
- Full Text :
- https://doi.org/10.1016/j.bbalip.2013.12.008