Molecular conformation of alamethicin in dimethylsulfoxide solution

Abstract

The solution conformation of alamethicin, a 20‐residue antibiotic peptide, has been investigated using two‐dimensional n.m.r. spectroscopy. Complete proton resonance assignments of this peptide have been carried out using COSY, SUPERCOSY, RELAY COSY and NOESY two‐dimensional spectroscopies. Observation of a large number of nuclear Overhauser effects between sequential backbone amide protons, between backbone amide protons and CβH protons of preceding residues and extensive intramolecular hydrogen bonding patterns of NH protons has established that this polypeptide is in a largely helical conformation. This result is in conformity with earlier reported solid state X‐ray results and a recent n.m.r. study in methanol solution (Esposito et al. (1987) Biochemistry26, 1043‐1050) but is at variance with an earlier study which favored an extended conformation for the C‐terminal half of alamethicin (Bannerjee et al. (1983) J. Mol. Biol.165, 757‐775).

The Legacy of G. N. Ramachandran and the Development of Structural Biology in India

“…Substantial progress was made during this phase in the crystallography of amino acids and peptides [38][39][40][41][42][43] , including the relevance of their supramolecular association to chemical evolution and origin of life 44 , nucleic acids and their constituents 45 , ionophores and related compounds 46,47 , and medicinally important molecules [48][49][50] . The same is true about NMR studies on medium-sized biomolecules [51][52][53] . The period also witnessed the beginnings of macromolecular crystallographic studies in India [54][55][56][57][58][59] .…”

Effects of Cα‐methyl substitution on the conformation of linear GnRH antagonist analogs

“…These observations are in agreement with the literature. Proximity of the peptide proton of the preceding Cx-substituted residue to the 6-protons of proline has been observed for Aib-Pro sequences in NOESY spectra of alamecithin solutions (17,18), and in crystallographic studies of (Pro-Aib), peptides, which form P-bend ribbon spirals (19).…”