[Impulse photolysis study of primary photoproducts of aromatic amino acids at 80 degrees K].
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Amino Acids↗
Biomedical subjects
E E Fesenko
Publications and source records attributed to E E Fesenko.
[Fast photo-induced changes in the light scattering of vertebrate photoreceptor membrane preparations. Study of suspensions of vesicles obtained by ultrasonic treatment of the outer segments of retinal rods].
By light scattering method it was shown, that vesicles, obtained by sonication of rod outer segment membranes in different ionic media rapidly and irreversibly increased their volume under bleaching of rhodopsin. Apparently, this volume change was caused by the increase in the amount of free ions in vesicles under illumination. The photoinduced volume change was practically the same in all cases studied (equal ionic constitutions inside and outside of vesicles; in the presence of penetrating anion SCN-; under ionic gradients on vesicle membranes; in the presence of ionophores which induce the permeability for K+ and H+) and corresponds to the appearance of no more than one ion inside the vesicle under bleaching of one rhodopsin molecule. The obtained results testify against the hypothesis, that bleaching of rhodopsin induce essential increase in ionic permeability of rod outer segment disk membranes.
Animals↗
[Molecular mechanisms of receptor-potential generation by the photoreceptor. I. Photic induction of a change in the permeability of artificial lipid membranes modified by photoreceptor membrane fragments].
Artificial lipid membranes modified by ultrasonic fragments of rod outer segments increase their conduction in response to illumination. Conduction increase is followed by the spontaneous foll in the dark to the unitial or somewhat higher level. The time constant of conduction increase was about 30 msec at room temperature, the constant of its following drop was about 300 msec; the activation energy of the last process was 19 +/- 3 kcal/mole.
Light↗
[Molecular mechanisms of receptor. II. Identification of the conformational transition of rhodopsin responsible for the leading edge of the photoresponse of artificial lipid membranes modified by fragments of the outer segment of rods].
Kinetic parameters of photoinduced permeability increase of artificial lipid membranes, modified by ROS fragments (tau20 degrees C = 20 mesec Ea = 33 +/- 2 kcal/mole) coincides with appropriate parameters of photoinduced protein fluorescence intensity decrease and ROS fragments absorption spectra change (metarhodopsin I leads leads to metarhodopsin II transition). Hydroxylamine accelerates this process, its rate is proportional to hydroxylamine at concentrations lower than 0.6 M.
Cell Membrane↗
[Molecular mechanisms of receptor-potential generation by the photoreceptor. III. Conformational transition responsible for the tail end of the photoresponse of an artificial lipid membrane modified by fragments of the external segments of rods].
The kinetics of photoinduced changes of protein fluorescence of cattle visual pigment was studied in the presence of hydroxylamine. The rate constant of fluorescence increase is proportional to NH2OH concentration when it is less than 0.4 M. It reaches the maximal magnitude (3.3 +/- 1 sec-1) at higher hydroxylamine concentration. Fluorescence increase rate is controlled by the rate of chemical reaction of rhodopsin with hydroxylamine. It is limited by conformational rearrangement of opsin. This rearrangement does not induce absorbance spectrum change of visual pigment, but confers to it the capability to react with NH2OH and NaBH4. Kinetic parameters of this rearrangement (tau 20 degrees C approximately 300 msec, Eact = 19 +/- 2 kcal/mole) coincide with kinetic parameters of diminishing of the photoresponse of artificial lipid membrane modified by fragments of rod outer segments in the temperature range studied (+2 divided by +25 degrees C).
Animals↗
[Protein kinase activity of bovine retina rod outer segments].
Dark-adapted pure bovine rod outer segments (ROS) (A280/A500--2.1) can be phosphorylated in the presence of [gamma-32P]ATP and [gamma-32P]GTP. The constant levels of phosphorylation, reached within 10--15 min, are 100 +/- 30 pmol 32P/nmol of rhodopsin for [gamma-32P]ATP and 2--4 pmol 32P/nmol of rhodopsin for [gamma-32P]GTP. These processes are not controlled by 10(-4)--10(-8) cAMP, cGMP or Ca2+, but are inhibited at higher concentrations of these agents. In the presence of histone the constant level of phosphorylation is increased up to 200 +/- 30 pmol 32P/nmol of rhodopsin for [gamma-32P]ATP, but is not changed when [gamma-32P]GTP is used. 10(-5) M cAMP is found to activate the phosphorylation in the presence of histone and [gamma-32P]ATP by 5--6 times. All this evidences that ROS contains cAMP-dependent protein kinase, which utilizes ATP, but not GTP. Moreover, ROS contains cyclic nucleotides- and Ca2+-independent protein kinase. These protein kinases are the ROS endogenous enzymes. This is shown in experiments on separation of pure ROS in a sucrose density gradient.
Adenosine Triphosphate↗
[Phosphorylation of endogenous proteins of bovine retina rod outer segments].
The components of bovine rod outer segments (ROS) and water-soluble extracts of ROS were separated by SDS-electrophoresis after incubation with [gamma-32P]ATP or [gamma-32P]GTP at different experimental conditions. After that gels were autoradiographed to reveal the phosphorylated intermediates. Our results suggest, that ROS contains the following protein kinase systems: 1) water-soluble cAMP-dependent protein kinases, that uses ATP, but not GTP, and phosphorylates the water-soluble 30 000 molecular weight protein; 2) protein kinase that uses GTP (probably, ATP also) and phosphorylates the 20 000 molecular weight protein in light-adapted ROS; 3) water-soluble cyclic nucleotide- and Ca2+-independent protein kinase that uses ATP rather than GTP and phosphorylates the water-soluble 70 000 molecular weight protein. The concentrations of phosphorylated intermediates in bovine ROS are estimated.
Adenosine Triphosphate↗
[Molecular mechanisms of photoreception. V. Reconstitution of a sodium channel on an artificial lipid membrane modified by bovine rod outer segment components].
An attempt is made to reconstitute the Na+-conductivity elements of rod outer segment (ROS) plasma membrane on the artificial lipid membrane (ALM). ALM were modified by preparation with bovine ROS plasma membrane fragments. Discrete fluctuations of the ALM conductivity were observed at addition of this preparation to the ALM bathing solutions to a final concentration of 0.1--1.0 microgram/ml. The magnitude of these fluctuations was about 25 pS at 140 mM NaCl. The modified ALM possessed preferentially the Na+-conductivity, which was at least five times as great as that for K+ or Li+. The modified ALM showed practically no conductivity for Cl-. The Na+-channels were voltage-dependent. The Na+-channels were "sensitive to visible light" at some experimental conditions. The optimal conditions were obtained for reconstitution of Na+-channel on the ALM. The temporal and termal stabilities of the modified preparation were investigated. It was shown that the frequency of the modified ALM conductivity fluctuations are dependent on temperature and on lipids composition of ALM. The data obtained in our work are in a good agreement with the results of electrophysiological studies of photoreceptor cells. It may be indicated, that the investigated ALM contains the Na+-channel of the ROS plasma membranes. It is suggested that the reconstituted system will be useful for studying the principles of regulation of ROS plasma membrane sodium conductivity and the nature of a mediator in a photoreceptor transduction mechanism.
Animals↗
[Conductance of cytoplasmic membrane of photoreceptors by the method of intracellular dialysis].
To clear up the effect of agents proposed as a mediator in the phototransduction process on the rod outer segment cytoplasmic membrane a technique based on the intracellular dialysis method was developed. It was shown that in the presence of nucleoside-triphosphates 3',5'-cGMP increased cytoplasmic membrane sodium conductance of dialyzed rod outer segment by 1-4 nS. The dependence of the effect amplitude on the cyclic nucleotides concentrations was obtained. It is suggested that the conductance changes observed are due to the action of cyclic nucleotide dependent protein kinase on the rod outer segment plasma membrane.
Animals↗
[Anion channels of photoreceptor cell plasma membranes].
In patch clamp study of the plasma membrane of the frog (Rana temporaria) retinal rod the anion channels uniformly distributed on the cell surface (0.1 channels micron-2) with the open state conductance (0.1 M NaCl) 200 +/- 30 p omega-1 were revealed.
Animals↗
[Molecular mechanisms of photoreception. IV. Photoregeneration of rhodopsin from metarhodopsin II using the artificial lipid membrane method for detection of intermediate steps of this reaction].
It was shown that photoregeneration of rhodopsin from metarhodopsin II takes place in bovine retinal rod outer segment disc membrane fragments. Photoregenerated rhodopsin is identical to unbleached rhodopsin in spectra and in stability to NH2OH. Moreover, as an unbleached pigment, photoregenerated rhodopsin can induce the transient increase of the artificial lipid membrane (ALM) conductivity in response to visible light. It was shown, that the UV-light converts metarhodopsin II to rhodopsin through the new long-lived (tau approximately 5 min) intermediate product (X500). X500 is indistinguishable from rhodopsin spectrophotometrically, but it can not induce the transient increase of ALM conductivity in response to visible light. It was shown that P467 (this product is obtained usually by photolysis of metarhodopsin II) has a retinal chromophore in all-trans configuration. This result indicates that P467 is produced from cis-metarhodopsin II and X500 (these products are the intermediates of the back reaction metarhodopsin II--rhodopsin) but not from metarhodopsin II as suggested earlier. A modified scheme of the back reaction metarhodopsin II--rhodopsin is given.
Animals↗
[Fast photo-induced changes in the light scattering of vertebrate photoreceptor membrane preparations. Study of a suspension of retinal outer rod segments].
It has been found that light induced a fast decrease of light scattering of suspensions of retinal rod outer segments. This decrease coincides in time with the decay of metarhodopsin I. Evidence is presented that this effect is conditioned by an increase of the interdisc volume due to a photoinduced increase of ion numbers in them. The value of the effect was practically independent of pH, ionic composition and osmomolarity of the medium. The effect amplitude was small (10% to the value of light scattering change induced by hypertonic shock) and in proportion to the value of bleached rhodopsin. Calculations in the basis of these data have shown that bleaching of a rhodopsin molecule brings about the appearance of no more than one ion in the interdisc volume. The results obtained are used to analyzed the validity of our proposition concerning the existence of ionic photoconductivity in the disc membranes of rod outer segments.
Animals↗
[Modification of the activity of murine peritoneal neutrophils upon exposure to millimeter waves at close and far distances from the emitter].
The comparison of horn, dielectric and channel antennae on their matching with various types of loads, including a biological object, is carried out. The channel antenna in contrast to dielectric and horn ones provides the uniform spatial distribution of specific absorbed rating in the frequency range used and wide-band matching with the object both in near field and far field zones of the radiator. It is shown, that low-intensity electromagnetic radiation of extremely high frequency in near field zone of the channel radiator modifies the activity of mouse peritoneal neutrophils on a quasi-resonance manner. The interaction of electromagnetic radiation with the biological object has been revealed in the narrow-band frequencies of 41.8-42.05 GHz and consists in inhibition of luminol-dependent chemiluminescence of neutrophils activated by opsonized zymosan. It is not found any frequency dependence of the electromagnetic radiation effects in the far field zone of the radiator. The results obtained suggest, that the quasi-resonance dependence of the biological effect on the frequency of the electromagnetic radiation in the near field zone is conditioned by structure and nature of the electromagnetic radiation in this zone.
Animals↗
[Electron microscopic analysis of the effect of modulated microwave radiation on isolated rat olfactory mucosa].
Isolated olfactory neuroepithelium and neighbouring respiratory epithelium of 6 Wistar rats after exposure to high frequency irradiation (the microwave carrier frequency was 0.9 GHz; the rectangular pulse modulation was 16 pulses per second; the pulse duration was 50%; the microwave power density in exposure glass chamber was 15 W/kg; the exposure time was 15 min) were studied using high resolution transmission electron microscopy. Ultrathin sections of both epithelia showed the drastic changes in ultrastructure of mucosa. Knobs of primary olfactory neurons and apical parts of supporting (sustacle) cells of the neuroepithelium showed strong vacuolization due to stimulating effect of the microwave irradiation on mucus secretion. The fusion of neighbouring cilia of respiratory cells was revealed. Such "giant cilia" contained more than 5-10 axonemes with basal bodies. In one case the mucus contained paracrystalline structures which were formed by microvilli and nonidentified filamentous protein (10 nm in dia). Degeneration of primary olfactory neuron axons was revealed.
Animals↗
[Single Ca2+-activated K+-channels in cultured kidney cells Vero].
Using the patch voltage-clamp method ("inside-out" mode) properties of single Ca(2+)-activated K+ channels in cultured kidney cell Vero were studied. Two types of kinetically distinct channels (fast and slow) were found. The fast and slow channels differ by single channel conductance, kinetic parameters, characteristics of interaction with Ca2+, and voltage dependency degree of the kinetics parameters, but are similar in ionic selectivity in respect to monovalent cations. It was found that the channel conductance varies from patch to patch between 140 and 230 pS. Average values of single channel open duration and an apparent dissociation constant were correlated with the single channel conductance. The relationship was found: the more the conductance the lesser the open time duration and more the dissociation constant. The data suggest that there is almost continuous spectrum of subtypes of the Ca(2+)-activated K+ channels, the fast and slow channels being extreme groups of this spectrum. The data are regarded from the viewpoint of the clustery hypothesis.
Animals↗
[Molecular mechanisms of biological action of low magnetic fields. I. Stability of chromatin from Ehrlich ascite carcinoma and mouse brain cells to the treatment of DNase 1 under combined action of low constant and alternating low-frequency magnetic fields adjusted to the cyclotron resonance of ions of polar amino acids].
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Animals↗
[Molecular mechanisms of biological action of low magnetic fields. II. Purification and characteristics of protein from rat brain chromatin which inhibit DNAse 1 activity].
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Animals↗
[Molecular mechanisms of biological action of low magnetic fields. III. Regulation of intermolecular interaction in water phase of DNA, DNAse 1 and a DNAase 1 inhibitor under combined action of low constant and alternating magnetic fields adjusted to cyclotron resonance of polar amino acid ions].
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Animals↗