The number of cooperative regions (energetic domains) in a pepsin molecule depends on the pH of the medium.

The technique of scanning microcalorimetry was used to study the effect exerted by ethanol and by the pH of the medium on the number and size of cooperative regions in a pepsin molecule. Ethanol addition lowered the temperature of protein denaturation, but did not change the number of energetic domains. The number of thermodynamic cooperative units (determined as a delta Hcal to delta Heff ratio) was reduced from four to two when the pH changed from 6.

[Number of cooperative regions (energy domains) in the pepsin molecule depends on the pH of the medium].

Ethanol and pH influence on the number and dimensions of cooperative regions in pepsin molecule was studied by scanning microcalorimetry. It is shown that ethanol solution causes a decrease of temperature of protein denaturation but does not influence the number of energetic domains. While changing pH from 6.

[A peptide, containing the universal antigenic determinant of tryptophanyl-tRNA-synthetase].

Among clostripain hydrolysate peptides of beef pancreas tryptophanyl-tRNA synthetase the peptide Ile-Ser-Phe-Pro-Ala-Ile-Asn-Gln-Phe-Ala-Ala-Pro-Ser-Gln-Phe-Ser-Ile-Arg was revealed which contains the continuous antigenic determinant for monoclonal antibody Am1. This antibody specifically cross-reacts with tryptophanyl-tRNA synthetases of procaryotes, eucaryotes and archebacteriae. The synthetic peptide with identical amino acid sequence plus N-terminal Arg residue (S-peptide), being immobilized on enzyme immunoassay (EIA) microtitration plate, also binds with Am1.

[Localization of energy domains in Bacillus intermedius 7P ribonuclease].

Two independently melting regions (energetic domains) were localized in Bacillus intermedius 7P ribonuclease by methods of circular dichroism and high resolution X-ray analysis: the lov-temperature melting domain, containing C-terminal region of the molecule with five strands in antiparallel beta-structure and the high-temperature melting alpha-helical domain in the N-terminal region. The contact between these domains is stabilized mainly by ionic interaction Asp-22 - Lys+-48. At pH 2.

[Staged equilibrium of carbonic anhydrase unfolding in strong denaturants].

It has been shown by 1H-NMR, circular dichroism, fluorescence and viscometry techniques that equilibrium unfolding of carbonic anhydrase B (a one-domain globular protein) in urea guanidine hydrochloride consists of two sequential stages. The first stage is connected with a decrease of intramolecular interactions, stabilizing the rigid tertiary structure and with the increase of mobility of aliphatic side chain groups. At the second stage the decrease of protein secondary structure and hydrophobic interactions take place as well as the increase of mobility of massive aromatic side chain groups.

[Spatial structure of secretin molecule].

By conformational analysis and circular dichroism the structure of peptide hormone secretin and its shortened N-terminal fragments in different solvents (water, aqueous solutions of alpha-L-phosphatidic acid and sodium dodecyl sulfate) have been studied. The results obtained by the two methods are compared.

[Secondary structure of proteins from circular dichroism spectra. V. Secondary structure of proteins in a "molten globule" state].

A method that accounts for the contribution made by aromatic amino acid residues in circular dichroism spectra of proteins has been used in order to analyze the structure of bovine carboanhydrase B, bovine and human alpha-lactalbumin in the native state and when denatured with acid and temperature. At acid- and temperature-induced transitions of the secondary structure of these proteins has been shown not to change. However the rigidity of their tertiary structure decreases (the environment of aromatic amino acid residues is made more symmetrical).

[Determination of the secondary structure of proteins from circular dichroism spectra. IV. Contribution of aromatic amino acid residues into circular dichroism spectra of proteins in the peptide region].

A new method for determination of the secondary protein structure from the CD spectra taking into account the contribution of aromatic amino acid residues is proposed. New proteins reference CD spectra for five secondary structures (alpha-helices, antiparallel and parallel beta-structures, beta-bends and irregular form) without contribution of aromatic residues are obtained. By means of this new method the secondary structure of sixteen different proteins was analysed.

[Purification of homogeneous gamma-cystathionase and study of its structure by circular dichroism].

Rat liver gamma-cystathionase has been purified to homogeneity (verified by SDS electrophoresis and ultracentrifugation). The secondary and tertiary structures of the enzyme were studied by circular dichroism spectra. Our studies revealed that the holoenzyme molecule comprises approximately 22% of alpha-helices, 14% of beta-structure, 14% of beta-bends, and 50% of unordered structure.

Compact state of a protein molecule with pronounced small-scale mobility: bovine alpha-lactalbumin.

We describe a novel physical state of a protein molecule which is nearly as compact as the native state and has pronounced secondary structure, but differs from the native state by the large increase of thermal fluctuations (in particular, by the large mobility of side groups). This state has been characterized in detail for the acid form of bovine alpha-lactalbumin as a result of the study of physical properties of this state by a large variety of different methods (hydrodynamics, diffuse X-ray scattering, circular dichroism and infrared spectra, polarization of the luminescence, proton magnetic resonance, deuterium exchange and microcalorimetry). It has been shown that bovine alpha-lactalbumin can be transformed into a similar state by thermal denaturation.

'Molten-globule' state accumulates in carbonic anhydrase folding.

Kinetics of folding and unfolding of bovine carbonic anhydrase B were monitored by circular dichroism, viscometry and esterase activity. It was shown that kinetic intermediate states accumulating in folding process reveal a native-like compactness and secondary structure but have a symmetrized average environment of aromatic side groups and no esterase activity. These properties allow one to consider these intermediate states as the 'molten-globule' state of a protein molecule previously described by us for several equilibrium forms of bovine and human alpha-lactalbumins and bovine carbonic anhydrase B.

Studies of the structure of bacteriophage lambda cro protein in solution. Analysis of the circular dichroism data.

The secondary and tertiary structures of bacteriophage cro protein were studied by circular dichroism. The pH dependence of this structure was investigated: cro protein is stable over pH 4.5-10.

[Role of zinc ions in the functioning of bovine tryptophanyl-tRNA-synthetase].

By means of atomic absorption spectroscopy up to 0.9 Zn2+ atom per molecule of bovine tryptophanyl-tRNA-synthetase (E. C.

[Secondary structure and amino acid composition of protein complex associated with the rod part of myosin molecule].

The secondary structure and amino acid composition of a protein complex (LMM-Rp) bound to the heavy chains (HC) of light meromyosin (LMM), and the secondary structures of LMM and its fractions obtained at an intermediate stage of LMM-Rp preparation were studied. The data obtained were compared with the similar ones for LMM HC and for the myosin light chains (LC). For the secondary structure study the data of CD-spectra were used.

[Determination of protein secondary structure from circular dichroism spectra. III. Protein-derived base spectra of circular dichroism for antiparallel and parallel beta-structures].

Protein-derived basic CD spectra for alpha-helix, antiparallel and parallel beta-structures, beta-bends and irregular form of proteins have been determined from the experimental CD spectra of six (myoglobin, lysozyme, ribonuclease A, papain, lactate dehydrogenase, subtilisin BPN') or seven (glyceraldehyde-3-phosphate dehydrogenase added) reference proteins and the analysis of the X-ray data. The secondary structures of thirteen proteins (seven reference and six additional ones) have been analysed using the basic CD spectra thus obtained. The data obtained have been compared with the results of the X-ray data analysis.

[Determination of the secondary structure of proteins from their circular dichroism spectra. I. Protein reference spectra for alpha-, beta- and irregular structures].

It is shown that to obtain the protein-derived basic CD spectra for alpha-helical, beta-structural and irregular regions it is necessary to use a common criterion for isolation of secondary structures for all the reference proteins. Using the "rigid" criterion proposed by Finkelstein, Ptitsyn, Kozytsyn and the "mild" one (as proposed by Levitt and Greer) isolation of the alpha- and beta-structural regions for 5 reference proteins (myoglobin, lysozyme, ribonuclease A, papain, lactate dehydrogenase) has been carried out. Using the f alpha, f beta and f irregular thus obtained and the experimental CD spectra of these proteins, the basic CD spectra for alpha-helical, beta-structural and irregular regions in the proteins have been calculated.

[Determination of the secondary structure of proteins from their circular dichroism spectra. II. Estimation of the contribution of beta-pleated sheets].

Protein-derived basic CD spectra for alpha-helical, beta-structural, beta-bends and irregular regions of the proteins have been determined from the experimental CD spectra of five reference proteins (myoglobin, lysozyme, ribonuclease A, papain, lactate dehydrogenase) with the knowledge of the fractions of the residues in the corresponding conformation. The alpha-helical and beta-structural regions of the reference proteins have been isolated from the X-ray data using the common "rigid" criteria for all the proteins, as proposed by Finkelstein and Ptitsyn. The residues in the beta-bend have been isolated using the data of Chou and Fasman and also three assumptions formulated in the present paper.

[Detection of allergy to antibiotics in dermatology--venereology practice].

A total of 205 stationary patients with and without drug disease were examined with the purpose of diagnosing allergy to the widely used antibiotics. The reaction of leucocytosis was used in the studies and the antibiotic concentration was increased up to 1 gamma/ml. Sufficiently high specificity of the reaction for diagnosis of the medicamentous allergy was determined.

[Manganese-oxidizing microorganisms inhabiting the phylloplane].

Manganese oxidizing microorganisms belonging to the genus Metallogenium were found in the phylloplane of various trees and grass plants. This is the first evidence that epiphytes participate in the transformation of mineral elements, and that microorganisms belonging to the genus Metallogenium can be found not only in fresh water and soil.