Intermolecular interactions in the crystalline structure of some polyhalogenated Di- And triamino Pyridines: Spectroscopical perspectives.

Supramolecular synthon is identified as a unit and provides important structural and energetic information in the study of organic crystals. However, the direct estimation of the supramolecular interaction remains challenging. In the present work six polyhalogenated di- or triamino pyridines were synthesised, their crystalline structure was characterised, and corresponding supramolecular synthons were studied using a combination of quantum mechanical calculations and FT-IR and Raman spectroscopy.

How do electron donating substituents affect the electronic structure, molecular topology, vibrational properties and intra- and intermolecular interactions of polyhalogenated pyridines?

Seven polyhalogenated pyridine derivatives bearing an amino or a hydroxyl group, either at the or position, were studied using a combined experimental and computational approach. The presence of an electron donating substituent strongly impacted on the geometry, electronic structure, electrostatic properties, molecular topology and vibrational characteristics of these compounds compared to the corresponding polyhalogenated pyridines. In particular the attention was focused on changes in wavenumbers, force constants and intensity of the seven in-plane Ring Normal Modes (RNMs).

Impact of fluorination and chlorination on the electronic structure, topology and in-plane ring normal modes of pyridines.

Seven partially and fully fluorinated/chlorinated pyridines were investigated by means of FT-IR and Raman spectroscopy combined with quantum chemical calculations, mainly aiming to detect how the nature and position of F and Cl substituents affect the in-plane ring normal modes (RNMs) of pyridines in terms of vibrational wavenumbers, force constants, IR intensities and Raman activities. Taking pyridine as the reference, the RNMs and some derived RNMs through coupling with related C-X (X = F, Cl) stretching vibrations were identified on the basis of their composition in terms of internal coordinates. The impact of fluorination and chlorination on these RNMs was also discussed from the perspective of frontier molecular orbitals (MOs), maps of the molecular electrostatic potential (MEP) and the molecular topology.

[The genetic and biochemical mechanisms of the development of diabetic nephropathy in children].

The mechanisms responsible for the development of microangiopathies in type diabetes mellitus (DM1) are complex and under extensive study. Fresh data on the pathogenesis of DM1 make it possible to direct actual ways to the studies aimed at preventing the complications of this disease. The purpose of this study was to examine the contribution of the polymorphic types of the VNTR polymorphism of endothelial NO-synthase gene (NOS3) and the I/D polymorphism of angiotensin-converting enzyme (ACE), the status of the proteolytic systems and lipid metabolic disturbances to the development of diabetic neuropathy (DN).

[Renaturation of bacterial metalloproteinases].

After denaturation by phenol or acid ethanol bacterial metalloproteinases secreted by Bacillus thermoproteolyticus and Bacillus megaterium cells can be renatured by dissolution in 99.7% formic acid with subsequent dilution of the solution and its neutralization with an appropriate amount of an alkali. Renaturation is optimal at pH 9.

[Isolation and properties of intracellular peptidase from Brevibacterium].

The intracellular peptidase of Brevibacterium E531, a lysine-producing bacterial species, was purified 6500-fold by chromatography on DEAE-cellulose and the affinity adsorbent H-Thr(But)-Phe-Pro-hexamethylene-diamine-Sepharose 4B and by gel filtration on Sephadex G-200. The enzyme displayed the maximum activity towards proline p-nitroanilide at pH 7.7-7.

[Pepsinogen activation by microbial proteinases].

Serine proteinase and metalloproteinase of Asp. oryzae, extracellular metalloproteinase of L. pneumophila and chymotrypsin-like proteinase of S.

[Isolation and properties of leucine aminopeptidase from Aspergillus oryzae].

Homogenious leucine aminopeptidase is purified from "oryzine"--mixture of enzymes produced by surface culture of Asperigillus oryzae using treatment with activated characoal, followed by DEAE-cellulose and hydroxylapatite chromatographies, Biogel P-100 gel-filtration and polyacrylamide-gel electrophoresis. The enzyme has pH optimum 9.0 and the molecular weight 37500 as estimated by gil-filtration through Sephadex G-100 (superfine) and SDS-polyacrylamide gel electrophoresis.

[Biospecific chromatography of Bacillus subtilis metalloendoproteinase and detection of multiple forms of the enzyme].

Metalloendoproteinase was isolated from protosubtilin, i.e. a mixture of enzymes produced by Bacillus subtilis, during adsorption on activated carbon and a subsequent biospecific chromatography on DNP--hexamethylene diamine--Sepharose 4B and gramicidin S--Sepharose 4B.

[Isolation and properties of the acid carboxypeptidase of Aspergillus oryzae].

Caboxypeptidase with pH optimum 4--5 for peptide substrates is isolated from "oryzine", the enzyme mixture produced by Aspergillus oryzae, by means of successive salt fractionation, Sephadex G-75 gel filtration, chromatography on amberlite IRC-50, hydroxylapatite, DEAE-cellulose and polyacrylamide gel electrophoresis. Its molecular weight, as determined by means of polyacrylamide gel electrophoresis in the presence of sodium dolecylsulphate, was found to be 37 000. The enzyme has a broad substrate specificity and does not possess dipeptidase and esterase activities.