Comparative X-ray and Fourier-transform-infrared investigations of conformational properties of bacterial and synthetic lipid A of Escherichia coli and Salmonella minnesota as well as partial structures and analogues thereof.
By using the X-ray and infrared spectroscopic characteristics of various synthetic analogues and partial structures of lipid A in the dried state, a comparison of these compounds with their natural counterparts was undertaken. As judged by their X-ray diffraction and infrared spectroscopic features, the compounds tested could be divided into two main groups. The first group covered those samples synthesized in accordance with a previously assumed structure, while those synthesized in accordance with present knowledge on the lipid-A primary structure formed the second group. Members of the first group were characterized by a liquid-like, alpha-type arrangement of their fatty acyl chains in a non-lamellar supramolecular structure, while all members of the second group formed bilayered phases with a much more ordered, beta-type conformation of their fatty acyl chains. Synthetic Escherichia coli-type lipid A (compound 506), proved to be essentially identical to its natural counterpart with respect to those conformational properties accessible by our methods. The synthetic hepta-acyl species of Salmonella minnesota lipid A (compound 516) revealed an unexpected conformational behaviour, whereby a fatty-acyl-chain packing could be detected which was different from the hexagonal arrangement found for all other compounds of the second group.
Labischinski
H
H
Robert-Koch-Institut des Bundesgesundheitamtes, Berlin.
Naumann
D
D
Schultz
C
C
Kusumoto
S
S
Shiba
T
T
Rietschel
E T
ET
Giesbrecht
P
P
D004926:Escherichia coli / Q000032:analysis*; D005227:Fatty Acids / Q000032:analysis; D008027:Light; D008050:Lipid A / Q000032:analysis*; D008968:Molecular Conformation; D015394:Molecular Structure; D012475:Salmonella / Q000032:analysis*; D012542:Scattering, Radiation; D013055:Spectrophotometry, Infrared / Q000379:methods; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
D005227:Fatty Acids; D008050:Lipid A