Bertil Erbing

Structure of the capsular polysaccharide from the Klebsiella K8 reference strain 1015

The structure of the capsular polysaccharide from the Klebsiella K8 reference strain 1015 has been elucidated. The structure was deduced from sugar analysis, different methylation analyses, a uronic acid degradation, and NMR spectroscopy. It is concluded that the polysaccharide is composed of pentasaccharide repeating units with the structure: [formula: see text] The structure differs from that of the previously published structure of the capsular polysaccharide from Klebsiella K8, which originates from another strain and has the following structure: [formula: see text] The serological similarity between the two strains is most likely derived from a common tetrasaccharide which is substituted in different ways in the two strains. Since the strain in the present investigation originates from the Klebsiella K reference strain collection of the International Escherichia and Klebsiella Centre, Copenhagen, Denmark, it is suggested that it should keep the designation K8. The other polysaccharide with Klebsiella K8 specificity should be renamed as K8,52,59 based on the cross-reactivity of the strain (I. Orskov, unpublished).

N.m.r. and conformational studies of some 3-O-, 4-O-, and 3,4-di-O-glycopyranosyl-substituted methyl α-D-galactopyranosides

Both 1H and 13C n.m.r. studies and conformational analyses have been performed on methyl α-D-galactopyranosides substituted in the 3-, 4-, and 3,4-positions with different anomeric forms of either L-fucopyranosyl or D-glucopyranosyl groups. Conformational analysis using the HSEA and GESA approaches indicated restricted rotational freedom around the glycosidic bonds of the trisaccharides compared to those of the disaccharides. It also indicated a number of proton-oxygen and proton-proton interactions which could be correlated to downfield and upfield glycosylation shifts, respectively, of the proton signals in both the di- and the tri-saccharides. Similar inter-residue atomic interactions could also be correlated to the 13C n.m.r. glycosylation shifts observed for the disaccharides and to some extent for the trisaccharides. Comparison was made between the observed glycosylation shifts of the trisaccharides and those calculated by using the glycosylation shifts for each disaccharide element. Large deviations, in most cases upfield shifts, were found for the signals for many linkage carbons.

N.m.r. and conformational studies of some 1,4-linked disaccharides

1 H and 13C N.m.r. studies and conformational analysis have been performed on eight 1,4-linked disaccharides in which the glycosidic linkages are in different stereochemical environments. The disaccharide glycosides have been divided into two groups, one containing α-DD-, β-LD-, and β-DL-glycosides, and one containing β-DD-, α-LD-, and α-DL-glycosides with typical chemical shift differences for each group. The conformational analysis, using the HSEA-approach, indicates a number of proton–oxygen and proton–proton interactions resulting in downfield and upfield shifts of the proton signals, respectively. The 13C n.m.r. glycosylation shifts obtained have been used to simulate spectra of polysaccharides containing 1,4-linkages.

The structure of the capsular polysaccharide from Klebsiella type 52, using the computerised approach CASPER and NMR spectroscopy

The structure of the capsular polysaccharide from Klebsiella type 52 has been elucidated using an improved and extended version of the computerised approach CASPER and NMR spectroscopy as principal methods. A previous suggestion to the structure but without the anomeric prefixes, could be shown correct [H. Björndal et al., Carbohydr. Res., 31 (1973) 93-100]. The polysaccharide has a hexasaccharide repeat with the following structure: [formula: see text]

Structural studies of a teichoic acid from Streptococcus agalactaie type III

An unusual type of teichoic acid has been isolated from Streptococcus agalactiae type III. It has the same backbone as the lipoteichoic acid from Streptococcus faecalis, but is devoid of fatty acid residues, a phosphatidyl group, and substituents in the poly(glycerol phosphate) side-chain. The following structure, with n approximately 20, was determined mainly with the aid of n.m.r. spectroscopy. (Formula: see text)

Galactosyltransfer in mouse mastocytoma: Purification and properties of N-acetyllactosamine synthetase

Abstract N-Acetyllactosamine synthetase (UDPgalactose: N-acetylglucosamine galactosyltransferase) was demonstrated in a microsomal fraction from mouse mastocytoma. A soluble enzyme fraction, recovered after treatment of the particulate enzyme with detergent and alkali, was further purified by affinity chromatography. The enzyme was eluted behind the main protein peak after chromatography on a column of Sepharose 4B, substituted with a derivative of N-acetylglucosamine. Under the conditions tested, however, only 15% of the enzyme applied to the column was recovered. Improved yields of the purified enzyme were obtained by chromatography of the solubilized enzyme on Sepharose gels containing α-lactalbumin. About one-third of the enzyme applied to such a column was adsorbed and purified approximately 570-fold. The purified enzyme was devoid of β-galactosidase (EC 3.2.1.23) as well as the galactosyltransferases previously shown to be present in the mastocytoma tissue Some kinetic parameters of a purified enzyme fraction have been determined.

Synthesis of some 3-O, 4-O, and 3,4-di-O-glycosyl-substituted methyl α-D-galactopyranosides

Seven disaccharide and eight trisaccharide methyl glycosides required for n.m.r. and conformational studies have been synthesized. They are all derivatives of methyl α-D-galactopyranoside which has been 3-O-, 4-O-, or 3,4-di-O-glycosylated with either L-fuco- or D-gluco-pyranosyl groups. All anomeric forms were synthesized, either via thioglycosides and methyl triflate promotion or via glycosyl bromides and silver triflate promotion.