Sjögren H, Ulvenlund S. Comparison of the helix-coil transition of a titrating polypeptide in aqueous solutions and at the air-water interface.
Biophys Chem 2006;
116:11-21. [PMID:
15911078 DOI:
10.1016/j.bpc.2005.01.007]
[Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Revised: 01/18/2005] [Accepted: 01/18/2005] [Indexed: 11/19/2022]
Abstract
The transition from alpha-helix to random coil of the titrating polyamino acid co-poly-L-(lysine, phenylalanine), (p-(Lys,Phe)), has been investigated as a function of pH and ionic strength in aqueous solution and at the air-water interface by means of circular dichroism (CD) spectroscopy and the Langmuir surface film balance technique. The results strongly suggest that the helix-coil transition for peptides at the air-water interface can be determined by using the two-dimensional Flory exponent, nu, to express the pH dependent peptide surface conformation. The helix-coil titration curve of p-(Lys,Phe) shifts approximately 2.5 pH units towards lower pH at the air-water interface, as compared with the bulk solution. This finding is of relevance for the understanding of conformation and conformational changes of membrane-transporting and membrane penetrating peptides as well as for the use of peptides in molecular devices.
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