NMR studies on the conformation, stability and dynamics of alamethicin in methanol.
 

NMR studies on the conformation, stability and dynamics of alamethicin in methanol.

http://www.bionmr.com//www.ncbi.nlm....ringerlink.gif Related Articles NMR studies on the conformation, stability and dynamics of alamethicin in methanol.

Eur Biophys J. 2020 Jan;49(1):113-124

Authors: Miura Y

Abstract
Alamethicin is an antibiotic peptide comprising 20 amino acid residues and functions as an ion channel in biological membranes. Natural alamethicins have a variety of amino acid sequences. Two of them, used as a mixed sample in this study, are: UPUAUAQUVUGLUPVUUQQO and UPUAUUQUVUGLUPVUUQQO, where U and O represent ?-aminoisobutyric acid and phenylalaninol, respectively. As indicated, only the amino acid at position six differs, and the two alamethicins are referred to as alamethicin-A6 and -U6, respectively. The conformation and thermal stability of alamethicin-A6 and -U6 in methanol were examined using proton nuclear magnetic resonance (NMR) spectroscopy. Both alamethicins form an ?-helix between the 2nd and 11th residues. The N-terminal, 19th and C-terminal residues take a non-helical conformation. The structure between the 12th and 18th residues has not been well determined due to the absence of cross peaks in the two-dimensional NMR data. The ?-helices are maintained up to 54*°C at least. In contrast to these similarities, it has been found that the length of the ?-helix of alamethicin-U6 is somewhat shorter than that of alamethicin-A6, the intra-molecular hydrogen bonds formed by the amide proton of the seventh residue is much more thermally stable for alamethicin-U6 than for alamethicin-A6, and the C-terminal residue of alamethicin-U6 has higher mobility than that of alamethicin-A6. The mobility of the N- and C-terminal residues is discussed on the basis of a model chain which consists of particles connected by rigid links, and the physiological significance of the mobility is emphasized.


PMID: 31912177 [PubMed - indexed for MEDLINE]



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