[Biopolymer fragments, containing glycosylphosphate residues. 12. Synthesis of glycosylphosphosugars, containing 2-acetamido-2-deoxy-alpha-D-mannopyranosylphosphate residues including a fragment of the Neisseria meningitidis A capsule antigen]. / Fragmenty biopolimerov, soderzhashchikh ostatki glikozilfosfatov. 12. Sintez glikozilfosfosakharov, soderzhashchikh ostatki 2-acetamido-2-dezoksi-alpha-D-mannopiranozilfosfata, v tom chisle fragmenta kapsul'nogoantigena Neisseria meningitidis A.

2-Acetamido-3,4,6-tri-O-benzoyl-2-deoxy-alpha-D-mannopyranosyl hydrogen phosphonate was synthesised and used for the first syntheses of glycosyl phosphosugars containing N-acetylmannosamine residue. The phosphodiesters prepared include ManNAc(alpha)-P-6Man(alpha)Me, an analogue of the fragment of some lysosomal glycoproteins, and ManNAc(alpha)-P-6ManNAc(alpha)Np, a derivative of the fragment of the capsular antigen from Neisseria meningitidis A.

[Sensitivity of mannosyl transferases from Salmonella serotype E1 and B to modification of the donor heterocyclic base]. / Chuvstvitel'nost' mannoziltransferaz iz salmonell serogrupp E1 i B k modifikatsii geterotsiklicheskogo osnovaniia donora.

A series of synthetic nucleoside diphosphate mannoses with different heterocyclic bases were tested as GDP-Man analogues in enzymatic mannosylation during assembly of O-antigen repeating units of Salmonella anatum and Salmonella typhimurium. The substrate efficiency was found to depend strongly on oxygen atom presence at C6 of the purine residue, the H2N-C2-N1-H grouping of the heterocyclic nucleus being less important. UDP-Man proved to be an efficient substrate for the mannosylation reactions.

[Specificity of the enzymes of Salmonella O-antigen biosynthesis. 6. Synthesis of sugar nucleotides with glycosyl phosphate activation. Analogs of guanosine diphosphate mannose modified at position 6 ofthe purine ring]. / Spetsifichnost' fermentov biosinteza O-antigena salmonell. 6. Sintez nukleotidsakharov s aktivatsiei glikozilfosfata. Analogi guanozindifosfatmannozy, modifitsirovannye po polozheniiu 6 purinovogo iadra.

Interaction of alpha-D-mannopyranosyl phosphate with diphenyl phosphochloridate gave the trisubstituted pyrophosphate which was converted through the reaction with nucleoside 5'-phosphates into nucleoside 5'-(alpha-D-mannopyranosyl)pyrophosphates. The method was used for preparation of guanosine diphosphate mannose analogs derived from adenine, purine, 2-aminopurine, 2-amino-6-methoxypurine, 2-amino-6-chloropurine, and 2-amino-6-mercaptopurine. These analogs are necessary for study on substrate specificity of mannosyltransferases of Salmonella O-specific polysaccharides biosynthesis.

Interaction of uridine diphosphate glucose analogs with calf liver uridine diphosphate glucose dehydrogenase. Influence of substituents at C-5 of pyrimidine nucleus.

The interaction of alpha-D-glucopyranosyl pyrophosphates of 5-X-uridines (X = CH3, NH2, CH3O, I, Br, Cl, OH) with uridine diphosphate glucose (UDPGlc) dehydrogenase (EC 1.1.1.22) from calf liver has been studied. All the derivatives investigated were able to serve as substrates for the enzyme. The apparent Michaelis constants for UDPGlc-analogs were dependent both on electronic and steric factors. Increase of substituent negative inductive effect lead to decrease of pKa for ionization of the NH-group in the uracil nucleus and, consequently, to a diminishing of the proportion of the active analog species under the conditions of assay. After correction for the ionization effect, the Km values were found to depend on the van der Waals radius of the substituent. The value of 1.95 A seems to be critical, as the analogs with bulkier substituents at C-5 showed a decreased affinity to the enzyme. The maximal velocity values of the analogs were also dependent on nature of the substituent. Good linear correlation between log V and substituent hydrophobic phi-constant was observed for a number of the analogs, although V values for the nucleotides with X = H, OH or NH2 were higher than would be expected on the basis of the correlation. The significance of the results for understanding of the topography of UDPGlc dehydrogenase active site is discussed.