[Deacetylation of chitin under homogeneity]. / Deatsetilirovanie khitina v gomogennykh usloviiakh.

Chitin isolated enzymatically from Antarctic krill shells was dissolved in aqueous NaOH by freezing and thawing to create homogenous conditions. Deacetylation was performed at room temperature or heating. The degree of deacetylation, molecular weight, and dynamic viscosity of solutions were estimated in chitosan samples. Deacetylation of chitin under homogenous conditions was optimized. Chitosans with molecular weights of 180-220 and 250-300 kDa were obtained from the chitins of Antarctic krill and Northern shrimps, respectively.

[A study of hydrolysis of various synthetic peptides with gastrointestinal enzymes using thin-layer chromatography]. / Issledovanie gidroliza nekotorykh sinteticheskikh peptidov fermentami zheludochno-kishechnogo trakta metodom tonkosloinoi khromatografii.

Hydrolysis in vitro of alpha- and epsilon-peptide bonds of synthetic amino acids and peptide substrates,--models of protein fragments, with digestive enzymes was studied. The kinetics of hydrolysis was studied by quantitative thin-layer chromatography followed by densitometric analysis of the chromatographic patterns. The rate constants of hydrolysis of Phe-Lys, Gly-Lys dipeptides and their epsilon-acetyl and epsilon-succinyl derivatives with leucine aminopeptidase and pancreatic enzymes were calculated. epsilon-Acyl residues of the substrates failed to split off under these conditions. The digestive enzymes hydrolysed the alpha-peptide bonds adjacent to the acylated lysine. Hydrolysis of epsilon-acetyl substrates proceeded faster as compared to epsilon-succinyl derivatives.

[Formation of muscle proteins during freezing]. / Strukturoobrazovanie myshechnykh belkov v protsesse zamorazhivaniia.

The effect of different conditions on the formation and properties of cryogels prepared by the freezing-thawing procedure from suspensions and solutions of the carp (Cyprinus carpio) myofibrillar proteins was studied. The freezing of water solutions and suspensions of the native myofibrillar proteins resulted in the formation of the structures mainly stabilized by non-covalent bonds. When muscle proteins were denatured prior to the freezing they formed the structures stabilized by both non-covalent and covalent disulfide bonds.

Ligand-exchange chromatography of nucleases.

The synthesis of chelating sorbents for ligand-exchange chromatography of enzymes is described. An inorganic support "Silochrom" and organic "Spheron", TSK-Gel HW 55 and cellulose were used as initial supports. The chelating sorbents contained iminodiacetic acid and iminodimethylphosphonic acid as stationary ligands. In order to obtain monofunctional sorbents, iminodiacetic acid was added in the form of its dimethyl ester. The concentration of stationary ligands on the sorbents varied from 10 to 100 mumol per ml sorbent. A chelating sorbent (in nickel form) was shown to be effective in the purification of exonuclease A5 from actinomyces. Electrophoretically homogeneous exonuclease A5 was obtained with a 25% yield. A chelating sorbent with iminodiacetic groups (in copper form) was applied to the isolation of endonuclease from Serratia marcescens directly from the culture medium. The capacity of the chelating sorbents for the endonuclease was studied as a function of the stationary ligand concentration. After one stage of purification, more than 70% pure enzyme was obtained with a yield exceeding 80%.

[Effect of peptides--structural analogs of NH2-terminal sites of fibrin alpha- and beta-chains--on specific binding of the NH2-terminal disulfide bond of fibrin with fibrinogen]. / Vliianie peptidov--strukturnykh analogov NH2 kontsevykh uchastkov alpha- i beta-tsepei fibrina--na spetsificheskoe sviazyvanie NH2-kontsevogo disul'fidnogo uzla fibrina s fibrinogenom.

Peptides Gly-Pro-Arg-Pro and Gly-His-Arg-Pro (fibrin alpha- and beta-chain NH2-terminal analogs, respectively) are studied for their effect on fibrinogen (F) and fibrin NH2-terminal disulphide knot (N-DSK) specific binding. Both peptides are found to inhibit the formation of soluble and insoluble F-N-DSK-complexes through inhibition of the interdomain D-E-binding. Gly-Pro-Arg-Pro is much more potent inhibitor than Gly-His-Arg-Pro. Lowering the insoluble F-N-DSK-copolymer quantity by concentration-dependent way these peptides do not change its composition described by the formula [F(N-DSK)2]n. Invariability of fibrinogen and N-DSK copolymer structure is asserted. In this structure neighbouring fibrinogen molecules are bound by two N-DSK molecules via the D1-E1 and D2-E2 binding sites.

An experimental approach to evaluation of the relative hydrophobic character of biological liquids and tissues.

Total proteins extractable from a number of rat tissues were partitioned in the aqueous Ficoll-400-Dextran-70 biphasic system. The partition coefficient of the total proteins extractable from a given tissue, K, was shown to be a tissue-specific constant. The free energy of transfer of a CH2 group from water to the aqueous solution of a given protein extract, delta(delta gCH2), was calculated from the corresponding K-value using the correlation relationship between K and delta(delta gCH2) reported earlier. It is suggested to use the parameter delta(delta gCH2)-value as a measure of the relative hydrophobic character of biological fluids and tissues. The difference between the delta(delta gCH2)-values for blood plasma medium and for a given tissue medium is used to quantify the difference in the relative hydrophobic character of the biological tissues and fluids under study. The possibilities to use the above characteristics in drug research are considered.

[The effect of structure and conformation on the relative hydrophobicity of dinucleosidephosphates and their analogs]. / Vliianie stroeniia i konformatsii na otnositel'nuiu gidrofobnost' dinukleozidfosfatov i ikh analogov.

Partition of a number of dinucleosidephosphates, their (2'-5')-isomers and a series of their analogues, in which the ribose ring was replaced by acyclic hydroxyalkyl substituents, in an aqueous biphasic ficoll--dextran system has been studied. Effect of the ionic composition of the biphasic system on partitioning of the compounds was examined. The relative hydrophobicity of the compounds in the presence of 0.11 M phosphate buffer, pH 7.4, and in the presence of 0.15 M NaCl in 0.01 M buffer, pH 7.4, was estimated. The results obtained are considered in regard to the effect of structure and conformation of a molecule on its affinity for an aqueous environment.

[Toxicological characteristics of disodium salt of N-lauroyl-L-glutamic acid--a surface-active agent used in the food processing industry]. / Toksikologicneskaia kharakteristika dinatrievoi soli N-lauroil-L-glutaminovoi kisloty--poverkhnostno-aktivnogo veshchestva dlia pishchevoi promyshlennosti.

To synthesize the disodium salt of N-lauroyl-L-glutamic acid (LG-Na2), use was made of the chloranhydride method with some modifications. The yield of the product was 85%. LG-Na2 possesses good surface-active properties and an emulsifying effect. The critical concentration of micelloformation of LG-Na2 is 6 10(-3) mol/l. LG-Na2 is a non-toxic compound. It is not cumulated in the animals' body. The LD50 for albino rats per os exceeds 10 000 mg/kg, that for mice 6500 mg/kg. It was shown in subacute experiments in rats that LG-Na2 did not produce any substantial influence on the animals' status or on some biochemical and morphological indicators of blood and organs. The authors suggest a tentative level of a safe oral action of LG-Na2 on man (10 mg per kg bw/day). LG-Na2 is likely to be widely used in food industry.

[Affinity chromatography of nucleases]. / Affinnaia khromatografiia nukleaz.

The review concerns isolation and purification of nucleases by affinity chromatography. Different stationary ligands and the methods for their immobilization on supports are described, along with diverse eluents and various procedures for a nuclease detachment from the affinity sorbents. The data on the affinity chromatography application for measuring the dissociation constants of the enzyme complexes with either immobilized or soluble ligands are compiled.

Effect of lipid composition on hydrophobic properties of liposomes.

Partition behavior of liposomes of different composition in the aqueous Ficoll-Dextran biphasic system was examined. The relative hydrophobicity of the liposomes was estimated. The effect of cholesterol on the solvent interactions of lecithin and sphingomyelin liposomes was studied. It is found that the effect of phosphatidylethanolamine on the hydrophobic character of lecithin liposomes exceeds that produced by cholesterol. The relative hydrophobicity of all the liposomes examined was found to be independent of the ionic composition of the system containing varied amounts of NaCl and Na-phosphate buffer, pH 7.4. The hydrophobic character of the liposomes under study is shown to increase in the following order: phosphatidylserine less than phosphatidylethanolamine less than phosphatidylcholine less than sphingomyelin. Hydrophobic properties of the liposomes are compared to those of human red cells. It is suggested that the dependence of the hydrophobic character of membrane particles on the ionic composition of an aqueous environment can be of fundamental importance for the selective distribution of the particles in vivo.

Characteristics of protein-aqueous medium interactions measured by partition in aqueous Ficoll-Dextran biphasic system.

Partitioning of a number of proteins in the aqueous Ficoll-400-Dextran-70 biphasic system was studied at pH 7.4 under varied ionic compositions. The relative hydrophobicities of the proteins have been estimated, and the contributions of the interactions of the ionogenic and non-ionic groups of a protein with an aqueous environment to the total hydrophobicity of the protein have been evaluated. Some arguments in support of the biological significance of the effect of ionic composition on the relative hydrophobicity of biological macromolecules are given. Possible applications of the partition technique to protein research are discussed.

Contribution to the investigation of the corn germ. Part II. Chemical composition of germ meal out of corn-oil cake.

The germ meal out of corn-oil cake contained up to 24.3% of protein, on the average. The main part of germ meal proteins was represented by the alkali-soluble fraction, up to 79.9%; the water-soluble proteins made up 7.3%, the salt-soluble--up to 4.6%, and alcohol-soluble--only up to 1%. With regard to the biological value, determined by fermentation hydrolysis, the total germ meal protein and its basic alkali-soluble fraction were not inferior to egg albumin and casein. The biological value of the test proteins, calculated by the aminoacid score, is nearing the biological value of an intact hen's egg and women's milk. The alkali-soluble fraction of germ meal protein has a high foam-forming ability and foam stability.

Physico-chemical factors governing partition behaviour of solutes and particles in aqueous polymeric biphasic systems. III. Features of solutes and biological particles detected by the partition technique.

The partition behaviour of human serum albumin and oxyhaemoglobin and several amino acids and small peptides was studied in the aqueous Ficoll-dextran biphasic system as a function of the ionic composition and pH. The partition coefficients of the solutes were expressed in terms of the equivalent number of CH2 groups, nCH2, and the equivalent number of carboxyl groups, m. The physical meaning of these two parameters and of the relationships found between them and pH for the proteins examined are discussed. A correlation was established between the difference in the relative hydrophobicities of the individual phases of various water-organic solvent systems and the interfacial tension, gamma 12, of the systems. It is argued that a relation of a similar type exists for the aqueous polymeric biphasic systems. The possibility of estimating the relative intensity of Van der Waals and hydration interactions of a solute and particle surface by examination of their partitioning in a biphasic system calibrated for the hydrophobic and hydration properties of the phases is discussed.

Correlation of hydrophobic character of opioid peptides with their biological activity measured in various bioassay systems.

Relative hydrophobicity of a series of enkephalin-like peptides has been studied by partitioning in the aqueous polymeric Ficoll-dextran biphasic system. The activities of the peptides in the guinea pig ileum, mouse vas deferens and rat brain receptor binding assay systems have been examined. The biological activities of the peptides in the two latter assays were correlated with their hydrophobic character. No correlation between the relative hydrophobicity of the compounds and their activity in the guinea pig ileum could be established. The correlations obtained appear to indicate that the drug-receptor interactions in the two bioassays occur under various conditions in regard to the local ionic composition at the membrane and/or the ionizable state of the receptor site. The activities of morphine and a number of similar drugs are described by a relationship different from that found for the peptides, which seems to support the multiple opiate receptor hypothesis.

[Relative hydrophobicity of mononucleotides and nucleosides determined by partition in aqueous two-phase polymeric system ficoll-dextran]. / Issledovanie otnositel'noi gidrofobnosti mononukleotidov i nukleozidov metodom raspredeleniia v vodnoi polimernoi dvukhfaznoi sisteme fikoll-dekstran.

The effect of ionic strength on the partition of several mononucleotides, deoxyribonucleosides and the corresponding bases in aqueous buffered (pH 7.4) ficoll--dextran biphasic system was examined. The relative hydrophobicity of the compounds at zero ionic strength was estimated in terms of an equivalent number of CH2 groups. It is found that the effect of the ionic strength on the relative hydrophobicity of the phosphate group is similar for all the mononucleotides examined but for the adenosine derivative.

[DNA immobilization on modified inorganic sorbents]. / Immobilizatsiia DNK na modifitsirovannykh neorganicheskikh sorbentakh.

Fragments of denaturated DNA having the length of about 500 nucleotides were immobilized, using silica carriers modified by organic polymers. It was shown that the organic coating allows to obtain sorbents, which practically exclude non-specific sorption with respect to DNA. The immobilization was carried out on hydroxyl-containing sorbents and on their phrosphorylated derivatives by means of water-soluble carbodiimide. The resulting preparations contained up to 60 units at A260 of DNA per 1 g of carrier. The effects of endonuclease A236, exonuclease A5 and pancreatic DNAse on the immobilized RNA were studied.

[Immobilization of methane-oxidizing bacterial cells]. / Immobilizatsiia kletok metanokisliaiushchikh bakterii.

The purpose of this work was to study how the conditions for immobilizing the cells of the methane oxidizing bacterium Methylomonas rubra using chemical and physical techniques influence their functional catalytical properties. These properties were found to depend on the chemical nature of a matrix and the mode of binding the cells to the carrier. The best carriers were shown to be silochrome with introduced carboxy groups and agar gel.

[Physico-chemical properties of water-soluble proteins from Spirulina platensis]. / Issledovanie nekotorykh fiziko-khimicheskikh svoistv vodorastvorimykh belkov Spriulina platensis.

By gel chromatography and polyacrylamide gel electrophoresis it was demonstrated that water-soluble proteins from Spirulina platensis contained components differing in their structure and having molecular weights ranging from 300,000+/-30,000 to 11,000 +/- 1,000. Electrophorectically the proteins were heterogeneous and their individual fractions differed in the number of pigment and protein components. The pigment-protein components were complexes in which the pigment was strongly bound to the protein. The protein components could be in a free state and in a pigment-bound state.