Structural studies by 1H NMR of a prototypic alpha-helical peptide (LYQELQKLTQTLK) and homologs in trifluoroethanol/water and on sodium dodecyl sulfate micelles
Authors
Young, John K.Mari, Frank
Xu, Minzhen
Humphreys, Robert E.
Clemente, Nikki M.
Stattel, James Michael Walker
Nelson, Donald J.
Gambino, Joseph
Wright, George E.
UMass Chan Affiliations
Department of Biochemistry and Molecular PharmacologyGraduate School of Biomedical Sciences
Document Type
Journal ArticlePublication Date
1997-08-01Keywords
Amino Acid Sequence; Magnetic Resonance Spectroscopy; Micelles; Models, Molecular; Oligopeptides; Protein Conformation; *Protein Structure, Secondary; Sodium Dodecyl Sulfate; Solvents; TrifluoroethanolLife Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
The 1H NMR-determined structure and dynamics of a synthetic, amphiphilic alpha-helical peptide, PH-1.0 (LYQELQKLTQTLK), and several homologs were compared in 50% trifluoroethanol-d2 (TFE-d2)/H20 and in sodium dodecyl-d25 sulfate (SDS-d25) micelles. The peptides were designed to test the influence on secondary structure of placement of favored and disfavored residues relative to a "longitudinal, hydrophobic strip-of-helix" defined by the repeating leucines. PH-1.0 was highly ordered as an alpha-helix in 50% TFE-d2/H20 and in SDS-d25 micelles. Homologs PH-1.1, in which L1 was replaced by T, and PH-1,4, in which L12 was replaced by T. were found to be partially helical in both media. Calculated structures in SDS-d25 revealed that the helix of PH-1.1 was slightly disordered at the N-terminus, but that of PH-1.4 was completely disordered at the C-terminus. Examination of distributions of hydrophobic residues in protein structures revealed that, when [symbol: see text] = LIVFM and [symbol: see text] = nonLIVFM, the pattern [symbol: see text] is favored and [symbol: see text] is disfavored in alpha-helices. Several analogs of PH-1.0 incorporating these patterns were studied. Peptide PH-1.12 (LYQELQKLLQTLK) retained alpha-helical structure in both 50% TFE-d2/H20 and in SDS-d25 micelles. However, although PH-1.13 (LYQELQKLTLTLK) was fully helical in 50% TFE, it was helical only through residue 6 in SDS micelles. Two homologs containing an additional loop of the helix and repeats of favored (PH-5.0, NYLQTLLETLKTLLQK) or suppressed LL patterns (PH-5.11, NYLQTLETLKLTQK) gave similar results, i.e. the latter peptide was helical only through residue 6 in SDS micelles. The degree of local order in these SDS micelle-adsorbed peptides correlates to placement of hydrophobic residues in motifs which are favored or disfavored in proteins in general and in alpha-helices specifically.Source
J Pept Res. 1997 Aug;50(2):122-31.
DOI
10.1111/j.1399-3011.1997.tb01177.xPermanent Link to this Item
http://hdl.handle.net/20.500.14038/34054PubMed ID
9273896Related Resources
ae974a485f413a2113503eed53cd6c53
10.1111/j.1399-3011.1997.tb01177.x