1H NMR Studies of Natural and Synthetic Immunostimulating Peptides in Aqueous Solution
- 3 March 2005
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 118 (2), 355-361
- https://doi.org/10.1111/j.1432-1033.1981.tb06410.x
Abstract
The peptides LAla-DGlu (L-alanyl-D-glutamic acid); LAla-DGlu[LLA2pm(Gly)]NH2, i.e., N2-(L-alanyl-D-.gamma.-isoglutaminyl)-N6-glycyl-LL-2,6-diaminopimelic acid; and LAla-DGlu[LLA2pm(Gly)-DAla], i.e., N2-(L-alanyl-D-.gamma.-glutamyl)-N6-glycyl-LL-.alpha.-2,6-diaminopimelyl-D-alanine, extracted from a Streptomyces strain, and their immunostimulating synthetic lauroyl deriatives were studied by 1H NMR spectroscopy at 270 MHz. The chemical shift analysis confirms the sequence of these compounds, the occurence of a .gamma.-bond between Glu (or GluNH2) and A2pm and the presence of a carboxamide group on the backbone of the tetrapeptide LAla-DGlu[LLA2pm(Gly)]. Temperature and pH studies strongly suggest that the tetrapeptide and pentapeptide exist under several folded conformations characterized by a proximity between the NH3+ group of Gly and the Glu (or GluNH2) residue. The similarity between the chemical shifts of the corresponding protons in LAla-DGlu, lauroyl-LAla-DGlu and muramyl-LAla-DGluNH2 shows that the coupling of the dipeptide with a lauroyl or a muramyl group does not induce significant changes in the structure of the peptide moiety. In the lipopeptide series the presence of the lauroyl chain leads to amphipathic substances which form micelles in aqueous solutions shown by the large increase of the proton linewidths. The immunostimulating properties of this kind of peptide manifest themselves at very low concentration and only after their coupling with a sugar or lipid moiety. These features can be interpreted by the fomation of mixed complexes between the immunoadjuvants and cell membrane constituents.This publication has 15 references indexed in Scilit:
- A short lipopeptide, representative of a new family of immunological adjuvants devoid of sugarLife Sciences, 1980
- 270‐MHz 1H Nuclear‐Magnetic‐Resonance Study of Met‐enkephalin in WaterEuropean Journal of Biochemistry, 1979
- Mode of action of iturin A, an antibiotic isolated from Bacillus subtilis, on Micrococcus luteusBiochemical and Biophysical Research Communications, 1978
- Nmr studies of aqueous solutions of tetra and branched peptides. I. Sequence determination of amino‐acid residues and the assignment of peptide hydrogen signalsBiopolymers, 1976
- Hydrosoluble immunostimulants of bacterial and synthetic originsCellular and Molecular Life Sciences, 1976
- Proton magnetic resonance relaxation studies on the structure of mixed micelles of Triton X-100 and dimyristoylphosphatidylcholineBiochemistry, 1975
- Minimal structural requirements for adjuvant activity of bacterial peptidoglycan derivativesBiochemical and Biophysical Research Communications, 1974
- Determination of an acidity scale for peptide hydrogens from nuclear magnetic resonance kinetic studiesJournal of the American Chemical Society, 1970
- Nuclear Magnetic Resonance Spectral Assignments from Nuclear Overhauser Effects1Journal of the American Chemical Society, 1965
- Nuclear Magnetic Resonance Study of the Protolysis and Ionization of N-Methylacetamide1Journal of the American Chemical Society, 1959