Nuclear overhauser effect and conformational states of cellobiose in aqueous solution

A nuclear Overhauser enhancement in α-cellobiose 1-phosphate, resulting from pre-irradiation of H-1′ of the non-reducing glucosyl group, was measured and calculated theoretically. Comparison of these data reveals a complicated conformational equilibrium in aqueous solutions of the cellobiose derivative.     

Plasmids for naphthalene biodegradation incompatible with IncP-2 and IncP-7 group plasmids

Fourteen conjugative naphthalene degradative plasmids have been classified by incompatibility. It is shown that the plasmids of IncP-9 group are characterized by the minor entry exclusion, with respect to the R plasmids belonging to IncP-2 or IncP-7 groups. On the other hand, the naphthalene degradative plasmids of incompatibility group P-7 exhibit a markedly pronounced entry exclusion, with respect to the R plasmids of the same incompatibility groups. Two naphthalene degradative plasmids reveal incompatibility with the reference plasmids of two Inc groups (P-2 and P-7). These plasmids control also resistance of bacterial cells to potassium tellurite, which is characteristic of the IncP-2 plasmids. Two other naphthalene degradative plasmids are capable of stable coexistence with the IncP-2, P-7 or P-9 reference plasmids.     

Synthesis of Pyridyl-4-Oxy-Substituted <Emphasis Type="Italic">N</Emphasis>-Hydroxy Amides of Cinnamic Acid as New Inhibitors of Histone Deacetylase Activity and Hepatitis C Virus Replication

Three structural isomers of pyridyl-4-oxy-substituted N-hydroxy amides of cinnamic acid (PyOCHA) have been synthesized for the first time. The relationship between their antiviral activity against hepatitis C virus (HCV) and inhibition of histone deacetylases of different cellular localization has been studied.     

Targeted mutagenesis identifies Asp-569 as a catalytically critical residue in T7 RNA polymerase

In order to look more closely at a well-conserved region in T7 RNA polymerase (T7 RNAP) containing, as shown earlier, the functionally essential residues Pro-563 and Tyr-571, we used targeted mutagenesis to change those residues within this region that are invariant in all single-subunit RNA polymerases, and characterized the mutant enzymes in vitro. The most interesting finding of this study was the crucial importance of the acidic group of Asp-569. In addition, we have shown that the phenolic ring is the most significant functional group of Tyr-571, with the hydroxy group also contributing to promoter binding.     

Substrate properties of C′-methyl UTP derivatives in T7 RNA polymerase reactions. Evidence for N-type NTP conformation

The number of synthetic UTP analogues containing methyl groups in different positions of the ribose moiety were tested as substrates for T7 RNA polymerase (T7 RNAP). Two of these compounds (containing substituents in the 5′ position) were shown to be weak substrates of T7 RNAP. 3′Me-UTP was neither substrate nor inhibitor of T7 RNAP while 2′Me-UTP was shown to terminate RNA chain synthesis. Conformational analysis of the analogues and parent nucleotide using the force-field method indicates that the allowed conformation of UTP during its incorporation into the growing RNA chain by T7 RNAP is limited to the χ angle range of 192–256° of N-type conformation.     

Selective cleavage of glycosidic linkages: Studies with the O-specific polysaccharide from Shigella dysenteriae type 3

Treatment of the O-specific polysaccharide from Shigella dysenteriae Type 3 with hydrazine in the presence of hydrazine sulphate resulted in quantitative N-deacetylation with the formation of a modified polysaccharide containing free amino groups. Oxidation of the modified polysaccharide with periodate did not destroy the 2-amino-2-deoxygalactose residues, thus indicating that they were substituted at position 3. Acid hydrolysis of the modified polysaccharide afforded 3-O-(2-amino-2-deoxy-β-D-galactopyranosyl)-D-galactose, which was identified as the N-acetyl derivative. Deamination of the modified polysaccharide with nitrous acid cleaved the 2-amino-2-deoxy-D-galactopyranosyl linkages to give a pentasaccharide as the major product, which appeared to be the modified chemical repeating unit of the O-specific polysaccharide.