Membrane interactions in small fast-tumbling bicelles as studied by P-31 NMR
2015 (English)In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1848, no 3, 760-766 p.Article in journal (Refereed) Published
Small fast-tumbling bicelles are ideal for studies of membrane interactions at molecular level; they allow analysis of lipid properties using solution-state NMR. In the present study we used P-31 NMR relaxation to obtain detailed information on lipid head-group dynamics. We explored the effect of two topologically different membrane-interacting peptides on bicelles containing either dimyristoylphosphocholine (DMPC), or a mixture of DMPC and dimyristoylphosphoglycerol (DMPG), and dihexanoylphosphocholine (DHPC). KALP21 is a model transmembrane peptide, designed to span a DMPC bilayer and dynorphin B is a membrane surface active neuropeptide. KALP21 causes significant increase in bicelle size, as evidenced by both dynamic light scattering and P-31 T-2 relaxation measurements. The effect of dynorphin B on bicelle size is more modest, although significant effects on T-2 relaxation are observed at higher temperatures. A comparison of P-31 T-1 values for the lipids with and without the peptides showed that dynorphin B has a greater effect on lipid head-group dynamics than KALP21, especially at elevated temperatures. From the field-dependence of T-1 relaxation data, a correlation time describing the overall lipid motion was derived. Results indicate that the positively charged dynorphin B decreases the mobility of the lipid molecules - in particular for the negatively charged DMPG - while KALP21 has a more modest influence. Our results demonstrate that while a transmembrane peptide has severe effects on overall bilayer properties, the surface bound peptide has a more dramatic effect in reducing lipid head-group mobility. These observations may be of general importance for understanding peptide-membrane interactions.
Place, publisher, year, edition, pages
2015. Vol. 1848, no 3, 760-766 p.
Bicelle, Solution P-31 NMR spectroscopy, Relaxation study, Membrane protein, Dynamic light scattering
IdentifiersURN: urn:nbn:se:su:diva-115668DOI: 10.1016/j.bbamem.2014.12.001ISI: 000349582500002PubMedID: 25497765OAI: oai:DiVA.org:su-115668DiVA: diva2:800090