Molecular model of the capsular polysaccharide of E. coli O86 clinical strain

Heteronuclear Correlation Spectra (proton & Carbon) of the RPS isolated from a mutant strain of Streptococcus

The Structure, Dynamics and conformation of oligosaccharides and polysaccharides are some of the interesting yet less studied among the bio-molecules. These carbohydrate structures are important as ligands as well as crucial structural framework of the living organisms. My study includes understanding the structure conformation and dynamics of these oligosaccharides.

The identification of the structure of a polysaccharide or an oligosaccharide includes identification of the sugar it is composed of, their anomeric configuration (alpha or beta), absolute configuration (D or L) and the linkage pattern. These studies were done with a series of receptor polysaccharides (RPS) isolated from the cell wall of certain streptococcal strain which colonizes in the oral cavity. The biosynthetic pathway of these polysaccharides was studied. Many new mutant polysaccharides were produced by genetic alteration of the biosynthetic gene clusters. The new polysaccharides were studied to determine their structure using high resolution NMR. This process includes a series of one dimensional as well as two dimensional NMR experiments to determine the chemical shifts of both the protons (non exchangeable) and carbons. Scalar coupling constants provides the information about anomeric configuration and identity of the sugar. Long range heteronuclear experiments were used to determine the linkage pattern. We have also developed a high-through put method to determine the structure of similar polysaccharides. The method has considerably decreased the time taken to determine the structure of similar polysaccharides. The study of RPS polysaccharides have provided critical insights towards understanding the mechanism of biosynthesis of these polysaccharides.