Effect of synthetic beta-carotene on the formation of cytolytic T-lymphocytes

The effect of intraperitoneal injection of beta-carotene in different doses on the formation of cytolytic T lymphocytes (CTL) in a one-way mixed lymphocyte culture (MLC) of allogeneic mice was studied. The maximal cytotoxic activity of lymphocytes was attained in the MLC with splenocytes of mice which received 10 mg/kg beta-carotene 6 days before experimentation. The correlation was studied between the beta-carotene ability to stimulate CTL formation and antineoplastic activity. It was discovered that injection of beta-carotene in doses and times provoking maximal CTL induction had no effect on the animals' lifespan and the size of transplanted sarcoma 180.     

Changes in the content and structure of the coenzyme A moiety in the liver of diabetic mice (db/db) administered a regimen of nicotinamide

Alterations in the content and structure of CoA moiety typical of hyperlipogenesis (a rise in total and free CoA levels, a drop in short-chained fatty acyl-CoA/CoA and long-chained fatty acyl-CoA/CoA ratios) were found in the liver of obese mice with non-insulin-dependent diabetes (db/db). The treatment of diabetic mice with nicotinamide, an antilipemic drug, was accompanied by a decrease in total and free CoA levels and a rise in short-chained fatty acyl-CoA content and short-chained fatty acyl-CoA/CoA and long-chained fatty acyl-CoA/CoA ratios, probably leading to the inhibition of the enzymes of primary lipogenesis steps. It is suggested that CoA moiety structure is essential as an integral index regulating the rate of fatty acid biosynthesis in diabetes mellitus.     

Improved rapid phosphotriester synthesis of oligodeoxyribonucleotides using oxygen-nucleophilic catalysts.

The use of different condensing and phosphorylating agents in conjunction with oxygen-nucleophilic catalysts, such as 4-substituted derivatives of pyridine N-oxide and quinoline N-oxide, leads to a dramatic increase of the rate of the phosphotriester bond formation and minimizes the amount of by-products caused by the modification of heterocyclic bases. The application of these catalysts to the solid-phase oligonucleotide synthesis allows to reduce the time needed for the performance of one elongation cycle on a polymer support to 10 min.     

<Emphasis Type="Italic">N</Emphasis>-azidomethylbenzoyl blocking group in the phosphotriester synthesis of oligoribonucleotides

An effective modification of the phosphotriester method has been developed for the automatic synthesis of DNA and RNA fragments using O-nucleophilic intramolecular catalysis and the 2-(azidomethyl)benzoyl group for the protection of the amino groups of nucleotide heterocyclic bases.     

Flagellin as an object for supramolecular engineering

A model of tertiary and quaternary structure of E. coli flagellin is suggested. According to this model, the molecule consists of two independent parts. One of them is formed by the N- and C-terminal regions of the polypeptide chain and is responsible for polymerization properties. The other consists of the central region of the polypeptide chain and composes that part of the molecular globule that forms the flagella surface. It is suggested that different artificial supramolecular structures can be constructed from flagellin molecules by varying the surface domain, i.e. the central part of the polypeptide chain, and by using the domain responsible for polymerization properties as a universal block for assembly. The simplest possible artificial supramolecular structures that can be constructed from flagellins of different strains are discussed.     

Synthesis and evaluation of some properties of chimeric oligomers containing PNA and phosphono-PNA residues.

In an attempt to improve physico-chemical and biological properties of peptide nucleic acids (PNAs), particularly water solubility and cellular uptake, the synthesis of chimeric oligomers consisted of PNA and phosphono-PNA analogues (pPNAs) bearing the four natural nucleobases has been accomplished. To produce these chimeras, pPNA monomers of two types containing N-(2-hydroxyethyl)phosphonoglycine, or N-(2-aminoethyl)phosphonoglycine backbone, were used in conjunction with PNA monomers representing derivatives of N-(2-aminoethyl)glycine, or N-(2-hydroxyethyl)glycine. The oligomers obtained were composed of either PNA and pPNA stretches or alternating PNA and pPNA monomers. The examination of hybridization properties of PNA-pPNA chimeras to DNA and RNA complementary strands in comparison with pure PNAs, and pPNAs as well as DNA-pPNA hybrids and DNA fragments confirmed that these chimeras form stable complexes with complementary DNA and RNA fragments. They were found to be resistant to degradation by nucleases. All these properties together with good solubility in water make PNA-pPNA hybrids promising for further evaluation as potential therapeutic agents.     

The reactivity of heme in biological systems: autocatalytic formation of both tyrosine-heme and tryptophan-heme covalent links in a single protein architecture

We have previously shown that introduction of an engineered Met160 residue in ascorbate peroxidase (S160M variant) leads to the formation of a covalent link between Met160 and the heme vinyl group [Metcalfe, C. L., et al. (2004) J. Am. Chem. Soc. 126, 16242-16248]. In this work, we have used electronic spectroscopy, HPLC, and mass spectrometry to show that the introduction of a tyrosine residue at the same position (S160Y variant) leads, similarly, to the formation of a heme-tyrosine covalent link in an autocatalytic reaction that also leads to formation of a second covalent link from the heme to Trp41 [Pipirou, Z., et al. (2007) Biochemistry 46, 2174-2180]. Stopped-flow and EPR data implicate the involvement of a tyrosyl radical in the reaction mechanism. The results indicate that the heme can support the formation of different types of covalent links under appropriate conditions. The generality of this idea is discussed in the context of other heme enzymes.     

The volumetric oxygen mass transfer coefficient in antibiotic biosynthesis liquids

This paper approaches the problem of oxygen mass transfer. This transfer is in antibiotic biosynthesis liquids produced by microorganisms belonging to the actinomycete and fungi classes, which exhibit a shear thinning non-Newtonian rheological behaviour. The volumetric oxygen mass transfer coefficients in these liquids (k_L a_b) change during biosynthesis processes. The change is mainly due to rheological parameter modifications, such as increasing the consistency index (K) and decreasing the flow behaviour index (n). The values of k_L a_b were 3.0–6.5 times lower than those recorded in water, and their decreasing depended on the k_L a values obtained without biological liquid and on the nature of fermentation broths, as well. Starting from experimental data, two correlations were established between k_L a_b and P/V,υ_SG and P/V,υ_SG, N, respectively. These correlations contain a dimensionless factor (η_am/η_g), which takes into account the rheological properties of the liquid phase and offers the possibility for a fast and sufficiently accurate estimation of k_L a_b. The empirical correlations developed in the paper correspond reasonably well with the relatively wide variety of experimental data, as in the model proposed by PEREZ and SANDALL , and allow for the comparison of the fermentation batches of the same or different microorganisms; also, they may be applied to the workings of design, scale-up, control and monitoring of bioreactors.