HAMLET Forms Annular Oligomers When Deposited with Phospholipid Monolayers
Författare
Summary, in English
Recently, the anticancer activity of human a-lactalbumin made lethal to tumor cells (HAMLET) has been linked to its increased membrane affinity in vitro, at neutral pH, and ability to cause leakage relative to the inactive native bovine alpha-lactalbumin (BLA) protein. In this study, atomic force microscopy resolved membrane distortions and annular oligomers (AOs) produced by HAMLET when deposited at neutral pH on mica together with a negatively charged lipid monolayer. BLA, BAMLET (HAMLET's bovine counterpart) and membrane-binding Peptide C, corresponding to BLA residues 75-100, also form AO-like structures under these conditions but at higher subphase concentrations than HAMLET. The N-terminal Peptide A, which binds to membranes at acidic but not at neutral pH, did not form AOs. This suggests a correlation between the capacity of the proteins/peptides to integrate into the membrane at neutral pH as observed by liposome content leakage and circular dichroism experiments and the formation of AOs, albeit at higher concentrations. Formation of AOs, which might be important to HAMLET's tumor toxic action, appears related to the increased tendency of the protein to populate intermediately folded states compared to the native protein, the formation of which is promoted by, but not uniquely dependent on, the oleic acid molecules associated with HAMLET. (C) 2012 Elsevier Ltd. All rights reserved.
Publiceringsår
2012
Språk
Engelska
Sidor
90-102
Publikation/Tidskrift/Serie
Journal of Molecular Biology
Volym
418
Issue
1-2
Dokumenttyp
Artikel i tidskrift
Förlag
Elsevier
Ämne
- Immunology in the medical area
- Microbiology in the medical area
Nyckelord
- alpha-lactalbumin
- membrane binding
- pore formation
- leakage
- AFM
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 1089-8638