Biomedical subjects

P Cescutti

Publications and source records attributed to P Cescutti.

21 records · Page 2Linked to original sources

PubMed1993

Structural investigation of the capsular polysaccharide produced by a novel Klebsiella serotype (SK1). Location of O-acetyl substituents using NMR and MS techniques.

The capsular polysaccharide of Klebsiella SK1 was investigated by methylation analysis, Smith degradation, and 1H NMR spectroscopy. The oligosaccharides (P1 and P2) obtained by bacteriophage phi SK1 degradation of the polymer were studied by methylation analysis, and 1D- and 2D-NMR spectroscopy. The resulting data showed that the parent repeating unit is a branched pentasaccharide having a structure identical to the revised structure recently proposed for Klebsiella serotype K8 capsular polysaccharide. [Formula: see text] The 2D-NMR data showed that one third of the glucuronic acid residues in the SK1 polymer are acetylated at O-2, O-3, or O-4. FABMS studies confirmed the presence of monoacetylated glucuronic acid residues. Thus, the relationship between the Klebsiella K8 and SK1 polymers is akin to that found for Klebsiella polysaccharides K30 and K33, which have been typed as serologically distinct yet their structures differ only in the degree of acetylation.

Acetylation↗

PubMed1993

Structural determination of the capsular polysaccharide produced by Klebsiella pneumoniae serotype K40. NMR studies of the oligosaccharide obtained upon depolymerisation of the polysaccharide with a bacteriophage-associated endoglycanase.

The Klebsiella pneumoniae K40 capsular polysaccharide has been isolated and investigated by use of methylation analysis, specific degradations and NMR spectroscopy. The polysaccharide was depolymerised by a bacteriophage-associated endogalactosidase, and the resulting oligosaccharide was characterised by one-dimensional and two-dimensional NMR spectroscopy and direct chemical ionisation MS. The repeating unit of the K40 capsular polysaccharide was shown to be a linear hexasaccharide with the composition-->3)- alpha-L-Rhap-(1-->2)-alpha-L-Rhap-(1-->4)-alpha-D-GlcpA++ +-(1-->2-)- alpha-D-Manp-(1-->2)-alpha-D-Manp-(1-->3)-alpha-D-Galp-(1--> (Rha, rhamnose).

Bacteriophages↗

PubMed1993

Solution properties of the capsular polysaccharide produced by Klebsiella pneumoniae SK1.

The solution properties of the capsular polysaccharide produced by Klebsiella pneumoniae SK1, SK1-CPS, were investigated by various methods. The SK1-CPS repeating unit is a branched pentasaccharide containing one glucuronic acid as single unit side chain; acetyl groups are present as non-carbohydrate substituents on the uronic acid residue in non-stoichiometric amounts. Chiro-optical, potentiometric, viscometric and rheological measurements have been performed in order to characterize the conformational behaviour of the polymer in water and in aqueous salt solutions. Under the investigated experimental conditions, changes of temperature, ionic strength and pH were shown not to induce any cooperative conformational transition. All the results obtained suggest that the solution conformation of SK1-CPS is a random coil with a certain degree of chain flexibility. The removal of the acetyl substituents apparently does not modify the overall conclusions drawn for the native polymer, except for an incipient tendency to aggregation revealed for high salt conditions.

Carbohydrate Conformation↗