Title
Spectroscopic and AFM characterization of polypeptide-surface interactions: Controls and lipid quantitative analyses
Author
Øyvind Strømland, Ørjan S. Handegård, Morten L. Govasli, Hanzhen Wen, Samuel Furse, Øyvind Halskau
Year
2017
Journal
Data in Brief
Abstract
This article is related to http://dx.doi.org/10.1016/j.bbamem.2017.01.005 (Ø. Strømland, Ø.S. Handegård, M.L. Govasli, H. Wen, Ø. Halskau, 2017) [1]. In protein and polypeptide-membrane interaction studies, negatively charged lipids are often used as they are a known driver for membrane interaction. When using fluorescence spectroscopy and CD as indicators of polypeptide binding and conformational change, respectively, the effect of zwitterionic lipids only should be documented. The present data documents several aspects of how two engineered polypeptides (A-Cage-C and A-Lnk-C) derived from the membrane associating protein alpha-Lactalbumin affects and are affected by the presence of zwitterionic bilayers in the form of vesicles. We here document the behavior or the Cage and Lnk segments with respect to membrane interaction and their residual fold, using intrinsic tryptophan fluorescence assays. This data description also documents the coverage of and solid-supported bilayers prepared by spin-coating mica using binary lipid mixes, a necessary step to ensure that AFM is performed on areas that are covered by lipid bilayers in the main experiments. Uncovered patches are detectable by both force curve measurements and height measurements. We tested naked mica׳s ability to cause aggregation as seen by AFM, and found this to be low compared to preparations containing negatively charged lipids. Work with lipids also carries the risk of chemical degradation taking place during vesicles preparation or other handling of the lipids. We therefor use 31P NMR to quantify the head-group content of commonly used commercial extracts before and after a standard protocol for vesicle production is applied.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Chemical stability, Vesicle interactions, Biochemistry