Lipopolysaccharides d'une Souche à Virulence Atténuée de Yersinia pestis

Lipopolysaccharides from a Slightly virulent strain of Yersinia pestis were investigated. Two types of lipopolysaccharides were obtained from the bacteria: lipopolysaccharide I was extracted with aqueous phenol/chloroform/hexane while lipopolysaccharide II was extracted with phenol/water. Chemical analysis of these lipopolysaccharides shows the presence of D‐glucose, galactose, glucosamine, L‐glycero, ‐D‐manno‐heptose, D‐glycero‐D‐manno‐heptose, 3‐deoxyoctulosonic acid, phosphate, 3‐hydroxymyristic acid, and small quantities of palmitic acid and palmitoleic acid. In addition, lipopolysaccharide II contains arabinose. Lipopolysaccharides I and II were methylated; analysis by gas‐liquid chromatography and by mass spectrometry indicated the presence of 2,3,4,6‐tetra‐O‐methyl glucose, 2,3,4,6‐tetra‐O‐methyl galactose and of tri‐, tetra‐ and penta‐methylated heptose derivatives. Arabinose in lipopolysaccharide II was not methylated and is therefore entirely substituted, while glucose and galactose are not substituted. Sodium metaperiodate nearly entirely oxidized glucose and galactose. Part of the heptose was not degraded by periodate oxidation, while part was converted into mannose. Lipopolysaccharides I and II could be the R and S forms of the lipopolysaccharide respectively, the S form containing an O‐specific chain with arabinose. The lipopolysaccharides were hydrolysed with acetic acid and degraded polysaccharides I and II were obtained. A large part of the arabinose was lost during the hydrolysis of lipopolysaccharide II into polysaccharide II, thus indicating that the arabinose might be in the furanose form. The absence of phosphate groups in polysaccharides I and II suggests the absence of bridges between the chains. However, if such bridges exist in the lipopolysaccharides, they are either on 3‐deoxyoctulosonic acid or on lipid A.