Comparative analysis of the spatial organization of myoglobins. I. Hydrophobicity profiles]

Hydrophobicity profiles of myoglobins in the animal species far remote in the evolutionary series are considerably similar. A complete coincidence as to the arrangement of hydrophobic zones along the polypeptide chain in myoglobins of the compared species (from a man to mollusc) is revealed at the beginning of alpha-helix of B-segment and in the area corresponding to a cluster which embodies a heme- bound water molecule, distal histidine E7 being directed to this cluster. The mollusc myoglobin with two absent (as compared to myoglobins of other species) hydrophobic sites differs in the profile of hydrophobicity most of all. It is supposed that hydrophobic nuclei forming the heme circumference create a globule "skeleton" thus pre-setting general spatial structure of the myoglobin molecule, which is very significant for its functional activity.     

Comparative analysis of the peroxidase activity of myoglobins in mammals

Studies have been made on the peroxidase activity of metmyoglobins in animals from various ecological groups--the horse Equus caballus, cattle Bos taurus, beaver Castor fiber, otter Lutra lutra, mink Mustela vison and dog Canis familiaris. It was found that the level of this activity in diving animals depends on the duration of their diving, whereas in terrestrial species--on the strength of muscular contraction.     

Comparative analysis of spatial EEG organization on models of non-verbal divergent and convergent thinking

Features of neurophysiological organization of two main thinking types playing different roles in creative processes, i.e., divergent and convergent were studied with participation of 30 right-handed male subjects at the age from 30 to 50 years. Two tests were presented: (1) creation of many visual images on the basis of two simple geometrical figures (the model of divergent thinking) and (2) classification of a figure element with one of the offered standard samples (convergent thinking). The number of created images or correctly classified elements for five minutes served a criterion of performance productivity. It was found that performance of the divergent test with high productivity (as compared to low productivity) was characterized by a greater increase in non-linear interactions between the cortical potentials, especially in the axis right frontal--left occipital areas. At the same time, under conditions of high productivity, the number of active narrow-frequency spectral-coherent EEG bands increased. The data confirm the notion of neurophysiological organization of creative processes, according to which creative processes require the intensification of retrieval operations (both conscious and unconscious), based on extensive interhemispheric interaction and involvement of a system of EEG coherent structures oscillating with different frequencies.     

Principles of spatial organization of cellular sheets]

The principles of the spatial organisation of epithelial sheets are described, and a new approach to studying their histoarchitecture is proposed. The approach is based on the concept of modular structure of tissues and consists in constructing a family of topological and geometrical models of tissue structure and their experimental verification. Theoretical evidence was obtained that at least 11 topological variants of cell mosaic patterns can be realized in simple epithelia but not one as has been suggested so far. Nine variants of epithelial mosaics predicted have been found experimentally in various animals, and the discovery of the other two is expected in the future. New thus far unknown properties of tissues such as translation symmetry and stoichiometry of the composition were described. By using this approach, it is possible to predict and find new variants of topology of multirow and multilayer epithelia and prognose their changes during normal and pathological morphogenesis.     

Comparative oxygen affinity of fish and mammalian myoglobins

Summary Myoglobins from rat, coho salmon (Oncorhynchus kisutch), buffalo sculpin (Enophrys bison) hearts, and yellowfin tuna (Thunnus albacares) red skeletal muscle were partially purified and their O₂ binding affinities determined. Commercially prepared sperm whale myoglobin was employed as an internal standard. Tested at 20°C, myoglobins from salmon and sculpin bound O₂ with lower affinity than myoglobins from the rat or sperm whale. Oxygen binding studies at 12°C and 37°C suggest that this difference is adaptive, permitting myoglobins from cold-adapted fish to function at physiologically relevant temperatures. Taken together, purification and O₂ binding data obtained in this study reveal a previously unrecognized diversity of myoglobin structure and function.     

Spectroscopic analysis of [Trp3]-beta-casomorphin analogs. Comparative structure conformation-activity studies

A series of [3-tryptophan]-beta-casomorphin-5([Trp3]-beta-CM-5) analogs were investigated by circular dichroism (CD) and fluorescence spectroscopy to explore their structure-conformation properties in solution. In addition, the comparative opioid activities of these compounds were evaluated using the in vitro guinea pig ileum (GPI) and mouse vas deferens (MVD) assays. Specifically, the pentapeptide sequence of [Trp3]-beta-CM-5, H-Tyr-Pro-Trp-Pro-Gly-OH (I) was modified at Pro-2 and Pro-4 by D-Pro substitutions to provide two diastereometric analogs, [Trp3-D-Pro-4]-beta-CM-5 (II) and [D-Pro2,4,Trp3]-beta-CM-5 (III). In the GPI and MVD assays, beta-CM-5 effected IC50 values of 1.3 microM and 8.9 microM, respectively, which confirmed its known mu/delta-selectivity on these two peripheral opioid receptor subtypes. The potencies of compounds I, II, and III were 0.2, 2.0, and less than 0.005 relative to beta-CM-5 on the GPI assay. Compounds I and II exhibited pronounced mu/delta-selectivities (greater than 18.9- and 12.4-fold respectively), whereas compound III was essentially inactive in both the GPI and MVD assays. CD studies of beta-CM-5 and its [Trp3]-beta-CM-5 analogs showed striking differences in their near-UV and far-UV spectra in aqueous or organic solvents. In the far UV CD spectra, weak (20%) alpha-helicity (maximum at 193 nm and minima at 208 and 222 nm) for beta-CM-5 was obtained in trifluoroethanol (TFE); however, none of the [Trp3]-beta-CM-5 analogs showed such CD bands. Of potential relevance to gamma-turn or C7 secondary structure was the observation of a strong negative band at 245 nm for compounds II and III which was not solvent-dependent in H2O or TFE, whereas compound I showed this CD band exclusively in TFE. In the near-UV CD at 275 nm (Trp electronic transition), the relative order of intensities of this band were determined for the [Trp3]-beta-CM-5 compounds to be II greater than I greater than III, which was identical to their relative biological potencies in both the GPI and MVD assays. Fluorescence energy transfer (FET) experiments of compounds I-III provided the intramolecular distances (r) between their Tyr (donor) to Trp (acceptor) side-chains, by the F?rster method, and were as follows: [Trp3]-beta-CM-5, r = 10.6 A; [Trp3, D-Pro4]-beta-CM-5, r = 9.6 A; and [D-Pro2,4,Trp3]-beta-CM-5, r = 11.0 A.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pig kidney Na+,K+-ATPase. Primary structure and spatial organization

cDNAs complementary to pig kidney mRNAs coding for alpha- and beta-subunits of Na+,K+-ATPase were cloned and sequenced. Selective tryptic hydrolysis of the alpha-subunit within the membrane-bound enzyme and tryptic hydrolysis of the immobilized isolated beta-subunit were also performed. The mature alpha- and beta-subunits contain 1016 and 302 amino acid residues, respectively. Structural data on the peptides from extramembrane regions of the alpha-subunit and on glycopeptides of the beta-subunit underlie a model for the transmembrane arrangement of Na+,K+-ATPase polypeptide chains.     

Use of methods of spectral-correlation analysis for studying the temporal and spatial organization of tissues]

Tissues within the organism represent multidimensional systems organized in time and space and having statistical dispersion in each parameter. Changes in its state may have a character of a monotonous trend and be periodical (the matter of chronobiology). The methods for detection of latent periodicities, developed in chronobiology, are applied for estimation of not only temporary but also spacial characteristics of the object. One of such methods is the calculation of the power spectrum of the autocorrelative function. Examples of its application are given.     

Comparative analysis of topological organization in Metazoa

Topological patterns in Metazoa, using previously elaborated methodology with employment of the genus of the surface (p) as topological invariant are considered. The term "density of the genus of the surface" is introduced. In sponges and in a lesser degree among Cnidaria and, Ctenophoria an increase of genus p up to indefinite high values and the shaping of topologically complicated quasifractal systems (irrigation system in sponges and gastro-vascular system in Radiata) are evident. In most Bilateria a stable topological pattern with open digestive tube is formed and subsequent topological complications of other systems may occur. Complicated topological patterns increasing the genus of the surface are evolved on the base of quasifractal systems: gut pockets in turbellaria, tracheal system in arthropods, bronchial system in birds, gills in bivalve mollusks, etc. Peculiarities of ordered and disordered topological patterns as well as topological origin of the increase of the genus of the surface are considered.     

Secondary structure in ribonuclease. II. Relations between folding kinetics and secondary structure elements

The kinetics of regain of 2′-CMP binding are monitored during renaturation of RNAase S. Experiments were performed by mixing equimolar amounts of S-peptide with S-protein. The S-protein fragment was incubated initially (i.e. before mixing with S-peptide) at pH 6.2 or 1.7 and various guanidine hydrochloride (GuHCl) concentrations. Three well-resolved phases are observed. The fastest phase is second-order. The reciprocal half-time increases linearly with fragment concentration and is independent of initial conditions for the S-protein fragment. An apparent on rate of k_on = 2 × 10⁵m^?1s^?1 is measured in 0.5 m-GuHCl (pH 6.2) and 20 ° C. Identical association kinetics are observed by changes in tyrosine absorbance. The fraction of native RNAase S formed in this second-order reaction strictly equals the fraction of S-protein molecules with intact β-sheet in initial conditions. The relation holds for different pH values, GuHCl concentrations and temperatures. The fraction of apparent helical content of S-protein in initial conditions may also vary but this is not reflected by the association reaction. We interpret this to mean that the β-sheet but not the α-helices must be preformed in initial conditions in order to generate the high-affinity peptide binding site of S-protein. Furthermore, it is concluded that the S-protein moiety β-sheet forms or unfolds in a single one-step reaction. 2′-CMP binding reports, additionally, two slower phases of renaturation. These are produced by S-protein molecules that have their β-sheet unfolded in initial conditions. It is observed that a unique dependence of these two folding rates exists for RNAase A, RNAase S and S-protein as function of t_m, the temperature of half-completion of thermal denaturation as measured by unfolding of the β-sheet in the respective compound in final conditions. The t_m value varies with changing pH, with GuHCl concentration and (for RNAase S) with changing fragment concentration. The findings are interpreted to argue in favor of a sequential mechanism of folding, where the stability of a structural precursor determines the rate of folding.     

Oxygen binding of myoglobins of diving animals]

When studying oxygen binding by myoglobins of diving animals it is shown that half-saturation of myoglobins obtained from the muscles of animals who can stop the external respiration for a long period of time occurs at oxygen strength of 0.62-0.67 mm Hg. Such indices of oxygenation of respiratory hemoprotein of muscles are characteristic of most mammals. Temperature being decreased from 37 to 15 degrees C, myoglobin affinity to oxygen considerably increases.     

Structural organization of [met]enkephalin and endorphin molecules. II. Theoretical conformation analysis of alpha-, gamma- and delta-endorphins]

Conformational energy calculations were carried out for neuropeptides alpha-, gamma- and delta-endorphins, which are 1-16, 1-17 and 1-19 fragments respectively, of beta-endorphin. The proposed computational scheme yielded all possible low-energy conformational sets for these hormones. Specific features of spatial organization of each compound and similarities of their structures are discussed.     

Spatial organization of cytochrome oxidase subunit II]

We have studied the tryptic digestion and cyanogen bromide cleavage of the tritium-labelled subunit II from bovine cytochrome oxidase. Basing on the radioactivity distribution in the peptides obtained we suggest a model for the spatial structure of the title subunit.     

Comparative analysis of EEG spatial organization in the rats with different level of genetically determinated anxiety under ethanol

The pecularities of EEG changes in the rats with geneticaly different level of anxiety was studed after ethanol injection. The biopotentials spatial synchronization and entropy in the "high anxious" rats (strain MR) did not increase under low dose; on the contrary the above changes were characteristic for the rats without anxiety signs (strain MNRA). After injection of middle and high ethanol doses the "high anxious" rats as compared with "low anxious" ones had the "simplification" of reaction type--the increase of narrow frequency coherence (i.e. linear biopotentials relationship) and spectral power of theta-activity (5.75-7.25 Hz), which was combined with the decrease of nonlinear biopotential characteristics. This fact is interpreted as the predominance of subcortical mechanisms of the brain functional state regulation over cortical ones. The significant decrease of high frequency EEG components in "high anxious" rats takes place under more high ethanol doses, presumably reflecting the increase of the anxiolytic level of ethanol effect.     

Primary structure of myoglobins from 31 species of birds

Primary structure of myoglobins (Mbs) from 31 avian species of 15 orders were reported, although portions of the structures in the 2 species could not be determined. At least 68 of the total 153 amino acid sites were invariant all through the avian, reptilian and human Mbs, and 20 of these sites were "internal", forming the internal hydrophobic cavities in which the heme group remains wrapped. Furthermore, at 27 sites, if replaced, the replacements were mostly conservative, and 13 of the conservative sites were "internal". Thus the all 33 "internal" sites, important for structural and functional stability of the protein, have been well preserved, either invariant or conserved, during evolution from reptiles to birds and mammals. The residue 71 (E14) in 4 penguin species was not deleted as previously reported in emperor penguin Mb but occupied by Gln. The residue 121 (GH3) was deleted in all 3 species studied of Falconiformes. Out of 9 anseriforms, 5 species of different genera showed the identical structure. Secondary structures as viewed by hydropathy profiles were highly similar throughout the reptilian, avian and mammalian Mbs.     

Neurochemical organization of reptilian thalamus. Comparative analysis of amniote optical centers

Study of neurochemical characteristics of the turtle thalamus was performed using antibodies against several biologically active compounds; monoamines (5-HT, TH), neuropeptides (SP, m-Enk, NPY), against ChAT and by histochemical detection of NADPH-d. Based on our own results and literature data obtained on other representatives of reptiles, birds, and mammals, a comparative analysis was carried out of neurochemical organization of two thalamic optical centers—relay nuclei of thalamofugal (GLd) and tectofugal (Rot/LP-Pulv) systems of amniotes. Features of similarities and differences of these centers in representatives of non-mammalian and mammalian amniotes are revealed. GLd has a great similarity of the studied neurochemical characteristics in all amniotes. It receives innervation from all studied transmitter-modulatory systems with predominance of serotonin-, choline- and NPY-ergic projections. Neurochemical organization of Rot comparable with the tectorecipient part of mammalian LP-Pulv has a great resemblance in reptiles and birds, with considerable interspecies differences inside each class. In the majority of the studied systems, Rot is characterized by scant innervation. On the contrary, LP-Pulv receives sufficiently massive innervation from these systems. The most characteristic of this complex are rich SP- and cholinergic projections that are scant in Rot of reptiles and birds. The similar feature of Rot and LP-Pulv is the presence of massive serotonin- and NO-ergic (NADPH-positive) projections. The revealed similarities and differences of the neurochemical characteristics of thalamic optical centers among amniotes seem to reflect various transformations of thalamo- and tectofugal visual systems in the course of phylogenetic and adaptive evolution.