[Activity of alpha-chymotrypsin immobilized in nanocapsules of poly(N,N-didodecyl-N,N-diallylammonium bromide)]. / Aktivnost' alpha-khimotripsina, immobilizovannogo v nanokapsuly poli(N,N-didodetsil-N,N-diallilammoniibromida).

Biocatalytic nanocapsule systems containing alpha-chymotrypsin in the inner aqueous cavity were synthesized. These systems can function in both organic solvents and aqueous media. To this end, the reversed hydrated micelles of N,N-diallyl-N,N-didodecylammonium bromide (DDAB) in cyclohexane (w0 = 22) with alpha-chymotrypsin encapsulated were subjected to UV-induced polymerization. After precipitation with acetone, the nanocapsules were transferred into water with the use of AOT and subsequent sonication. The unilamellar liposomes thus formed have an inner monolayer from the polyDDAB network, an outer monolayer from the AOT molecules, and contain alpha-chymotrypsin in the inner aqueous medium. According to the light scattering data, the mean outer diameter of the nanocapsules is 20 nm. When compared with free enzyme in respect to p-nitrophenyl acetate hydrolysis, the alpha-chymotrypsin encapsulated in the liposomes exhibits the same K(m) value, but its values of kcat and of the inhibition constant by the reaction product Kp decreased by factors of 1.2 and 1.6, respectively. The alpha-chymotrypsin immobilized in the nanocapsules is thermally stable and catalytically active up to 80 degrees C. The polymer network hinders conformational rearrangements of the enzyme molecule upon heating.

[Conformational analysis of biologically active thyroliberin analogs by two-dimensional NMR spectroscopy]. / Konformatsionnyi analiz biologicheski aktivnykh analogov tiroliberina metodami dvumernoi spektroskopii IaMR.

Preferable conformations of thyrotropin-releasing hormone (TRH, Glp-His-Pro-NH2) and its analogues Glp-Glu(R)-Pro-NH2 (R = NHCH(CH3)CH2Ar), Glp-Gln-Abu-NH2, Dho-Gln-Abu-NH2 in DMSO solution are determined using two-dimensional 1H NMR spectroscopy (delta-J-correlated, COSY and NOESY). Torsion angles psi i and chi i for every amino acid were calculated on the basis of the spin-spin coupling constants 3JNH-C alpha H and 3JC alpha H-C beta H values. The NOESY data were used for selecting the peptide conformations realized in solution. Distances between protons interacting by the dipole mechanism (d-contacts) were calculated using NOE values. These experiments allow one to estimate the torsion angles psi (between C alpha H-CO). TRH has an intramolecular H-bond between NH2-protons and His carbonyl with the torsion angles omega 3 = 180 degrees and psi 3 = 0 degrees. It is formation of this H-bond that apparently promotes the domination of the trans configuration of the His-Pro peptide bond. An intramolecular NH2-C alpha CO (Glp) H-bonding is revealed in other investigated compounds. It is known that a similar conformation of the TRH is realized in the course of its interaction with receptor.

[Conformational properties of biologically active melanostatin analogs]. / Konformatsionnye osobennosti biologicheski aktivnykh analogov melanostatin.

On the basis of the two-dimensional 1H NMR studies the conformation of melanocyte inhibiting hormone (HCl.Pro-Leu-Gly-NH2, MIF) and its five analogues with p-substituted phenylalanine has been determined. Structure-antidepressant activity relationship (examined by the Porsolt test) of MIF and its analogues has been estimated by means of the multivariate statistical analysis, the vicinal spin coupling constants, which determine phi and chi dihedral angles of the second amino acid and phi and dihedral angle of glycine, being selected as structural parameters. It is shown that a biologically active conformation (10-membered beta-turn II) is realized for the considered peptides.

[Ferricyanide ion binding sites on the surface of lecithin liposomes]. / Mesta sviazyvaniia ferritsianid-ionov na poverkhnosti letsitinovykh liposome.

Interaction of ferricyanide ions with sonicated lecithin liposomes has been studied by (1)H-NMR. Ferricyanide induced shifts have been shown to change along the choline chain of the lecithin head group. The magnitude of the shift decreases as the distance from the positive end of zwitterionic moiety increases. It is concluded that ferricyanide ions bind to the positive charged ammonium groups of the phospholipid.

[Influence of the structure of lecithins on their interaction with cholesterol]. / Vliianie struktury letsitinov na ikh vzaimodeistvie s kholesterinom

Interaction between cholesterine and phosphatidilcholines (PC) of three types: 1,2-disaturated (SS), 1,2-diunsaturated (UU) and 1-saturated-2-unsaturated (SU) was studied in bilayer vesicular membranes (BVM) by means of NMR-1H spectroscopy. BVM were obtained by sonification of aqueous (D2O) dispersions of individual (PC) and their mixtures. It is found that molecular special specificity of the interaction between PC AND cholesterine is preserved not only during phase division but also in the case when all the phospholipid components of the bilayer are in a liquid crystal state. At low content of cholesterine it favourably interacts with UU-PC, further on with the increase of concentration cholesterine starts to interact with SU- and SS-types of PC. It has been shown that such behaviour of cholesterine can not be explained by means of static models, i.e. by the differences in stability of its stechiometric complexes with CP molecules of different types. An attempt has been undertaken to interpret the selective character of PS-cholesterine interaction proceeding from the suggestion about the anisotropic character of lateral diffusion in the membranes, consisting of various structural types of PC.