Conformational studies of peptides representing a segment of TM7 from H+-VO-ATPase in SDS micelles.
The conformation of a transmembrane peptide, sMTM7, encompassing the cytoplasmic hemi-channel domain of the seventh transmembrane section of subunit a from V-ATPase from Saccharomyces cerevisiae solubilized in SDS solutions was studied by circular dichroism (CD) spectroscopy and fluorescence spectroscopy of the single tryptophan residue of this peptide. The results show that the peptide adopts an alpha-helical conformation or aggregated beta-sheet depending on the peptide-to-SDS ratio used. The results are compared with published data about a longer version of the peptide (i.e., MTM7). It is concluded that the bulky, positively charged arginine residue located in the center of both peptides has a destabilizing effect on the helical conformation of the SDS-solubilized peptides, leading to beta-sheet formation and subsequent aggregation.
Duarte
Afonso M S
AM
Laboratory of Biophysics, Wageningen University, 6703 HA Wageningen, The Netherlands.
de Jong
Edwin R
ER
Koehorst
Rob B M
RB
Hemminga
Marcus A
MA
D000595:Amino Acid Sequence; D002462:Cell Membrane; D002942:Circular Dichroism; D008823:Micelles; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D012995:Solubility; D013050:Spectrometry, Fluorescence; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry*
D008823:Micelles; D010446:Peptide Fragments; D012967:Sodium Dodecyl Sulfate; D025262:Vacuolar Proton-Translocating ATPases