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1.
Tatsuo Suzuki Michio Sugahara Katsu Azuma Masami Azuma Yoshiro Saimi Yuji Kito 《BBA》1974,333(1):149-160
The ultraviolet absorbance of squid and octopus rhodopsin changes reversibly at 234 nm and near 280 nm in the interconversion of rhodopsin and metarhodopsin. The absorbance change near 280 nm is ascribed to both protein and chromophore parts. Rhodopsin is photoregenerated from metarhodopsin via an intermediate, P380, on irradiation with yellow light (λ > 520 nm). The ultraviolet absorbance decreases in the change from rhodopsin to metarhodopsin and recovers in two steps; mostly in the process from metarhodopsin to P380 and to a lesser extent in the process from P380 to rhodopsin. P380 has a circular dichroism (CD) band at 380 nm and its magnitude is the same order as that of rhodopsin. Thus it is considered that the molecular structure of P380 is close to that of rhodopsin and that the chromophore is fixed to opsin as in rhodopsin. In the change from metarhodopsin to P380, the chromophore is isomerized from the all-trans to the 11-cis form, and the conformation of opsin changes to fit 11-cis retinal. In the change from P380 to rhodopsin, a small change in the conformation of the protein part and the protonation of the Schiff base, the primary retinal-opsin link, occur. 相似文献
2.
Motoyuki Tsuda 《BBA》1978,502(3):495-506
In the photoregeneration process of squid rhodopsin, an intermediate has been found at neutral pH values (phosphate buffer) with a flash light (λ > 540 nm). An intermediate R430, with the 11-cis retinal as chromophore, is produced from metarhodopsin in light and is converted to rhodopsin through the processes R430 → P380 and P380 → rhodopsin. The pH dependence of the velocity of the conversions suggests that processes R430 → P380 and P380 → rhodopsin involve a protolytic reaction and that the ionized group is a histidine residue of opsin. Kinetic parameters show that the largest conformational change in opsin occurs in the conversion of R430 → P380. 相似文献
3.
The axial and radial shrinkage of bovine rod outer segments, monitored by near-infrared scattering changes (P-signal), is investigated in dependence on the intensity of the activating flash. Suspensions of axially oriented and randomly oriented rod outer segments were measured. In the latter case, axial and radial effects are superimposed to another. The following results are obtained:
- The axial signal (P a, Τ≈10 ms) and the radial signal (P r, Τ=40–100 ms), simultaneously measured on axially oriented rod outer segments, are similarly saturated with a half-saturation at a rhodopsin turnover of 3.5%.
- For the saturation of the signal amplitude, measured on randomly oriented rod outer segments, a good fit is obtained by: $$\begin{gathered} P\left( \varrho \right) \sim 1 - e\beta \varrho , \hfill \\ \varrho : relative rhodopsin turnover by the flash; \hfill \\ \beta is found in the range 23 \leqslant \beta \leqslant 27 in all measurements \hfill \\ \end{gathered} $$
- The kinetics of the signal, also measured on the isotropic sample, depends on the rhodopsin turnover, the apparent time constant becoming faster with increasing turnover. The distortion of the signal cannot be fitted by a sum of exponentials with a fixed set of time constants.
4.
Bumps were recorded in Limulus ventral nerve photoreceptor as deflections in membrane voltage during 10 s illuminations by dim light which were repeated every 20 s. The bump amplitude vs frequency distribution and its dependence on the intensity of a preadapting light flash are described. Light adaptation which diminishes the average bump amplitude alters the character of the bump amplitude distribution from a curve with a convex region to a continuously falling concave curve. Weak light adaptation can increase frequency (and height) of the bumps elicited by constant stimuli. Raising the external Ca2+-concentration from 10 to 40 mmol/l augments the effect of a preadapting light flash in diminishing the bump amplitudes and also increases the bump frequency. The results are consistent with the assumptions that light adaptation is based on a Ca2+-dependent reduction of the amplification factor which determines the bump size and that the coupling between light induced rhodopsin reactions and bump generation is Ca2+-dependent. 相似文献
5.
T. Hariyama A. Terakita V. B. Meyer-Rochow 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,173(5):615-619
- Relative retinal amounts in the compound eye of the Antarctic amphipod Orchomene plebs were assessed during conditions of continuous summer daylight every 3 h over a period of 48 h. The habitat of the experimental animal is the bottom of the Ross Sea (78°S; 166°E) down to depths of at least 400 m; water temperature is a constant — 1.8° C. A periodicity of 12 h was detected with relative amounts of 11-cis retinal exhibiting peaks at midday and at midnight and troughs at 7.00 h and 19.00 h.
- The result that 90% of retinoid were insoluble in n-hexane suggests that at least 90% of the measured retinoid were attached to membrane-bound proteins such as opsin.
- Selective light adaptation showed that the visual pigments were thermostable and photoregenerable. The main absorbance peak of rhodopsin, compared with metarhodopsin, seems to be in the longer wavelengths.
6.
M Tsuda 《Biochimica et biophysica acta》1978,502(3):495-506
In the photoregeneration process of squid rhodopsin, an intermediate has been found at neutral pH values (phosphate buffer) with a flash light (lambda greater than 540 nm). An intermediate R430, with the 11-cis retinal as chromophore, is produced from metarhodopsin in light and is converted to rhodopsin through the processes R430 leads to P380 and P380 leads to rhodopsin. The pH dependence of the velocity of the conversions suggests that processes R430 leads to P380 and P380 leads to rhodopsin involve a protolytic reaction and that the ionized group is a histidine residue of opsin. Kinetic parameters show that the largest conformational change in opsin occurs in the conversion of R430 leads to P380. 相似文献
7.
Hydrogen ion changes of rhodopsin. pK changes and the thermal decay of metarhodopsin II380 总被引:2,自引:0,他引:2
S E Ostroy 《Archives of biochemistry and biophysics》1974,164(1):275-284
The ionization changes during the photolysis of the visual pigment, cattle rhodopsin, have been measured by simultaneous recording of spectral and pH changes. The thermal intermediates of rhodopsin and pH changes were recorded over a pH range of 4.6–8.9.In the normal sequence of intermediate changes at pH values of 5.4–7.7, the proton uptake of rhodopsin during the metarhodopsin I478 to II380 reaction is followed by a proton release in the thermal decay of metarhodopsin II380 to III465. Below pH 5.4, no proton release is observed during the thermal decay of metarhodopsin II380, and the metarhodopsin II380 appears to thermally decay directly to N-retinylidene-opsin440. Above pH 7.7, the major process appears to be a proton release and the final product is N-retinylidene-opsin365.The ionization state of certain groups in rhodopsin appears to control the metarhodopsin I478 to II380 reaction and control the products in the thermal decay of metarhodopsin II380. The pK changes of certain groups in rhodopsin may be the major factor in determining sequence of thermal intermediates and the values of the kinetic activation parameters. The reversing ionization changes may be important to the transduction process. 相似文献
8.
The photochemical intermediate metarhodopsin II (meta II; lambda max = 380 nm) is generally identified with rho*, the conformation of photolyzed rhodopsin which binds and activates the visual G-protein, Gt [Emeis, D., & Hoffman, K.P. (1981) FEBS Lett. 136, 201-207]. Purified bovine rhodopsin was incorporated into vesicles consisting of dimyristoylphosphatidylcholine (DMPC), and the rapid formation of a photochemical intermediate absorbing maximally at 380 nm was quantified via both flash photolysis and equilibrium spectral measurements. Kinetic and equilibrium spectral measurements performed above the Tm of DMPC showed that Gt, in the absence of GTP, enhances the production of the 380-nm-absorbing species while reducing the concentration of the 478-nm-absorbing species, metarhodopsin I (meta I), in a manner similar to that observed in the native rod outer segment disk membrane. This Gt-induced shift in the equilibrium concentration of photointermediates indicated that the species with an absorbance maximum at 380 nm was meta II. The presence of rho* in the DMPC bilayer was established via measurements of photolysis-induced exchange of tritiated GMPPNP, a nonhydrolyzable analogue of GTP, on Gt. Above Tm, the metarhodopsin equilibrium is strongly shifted toward meta I relative to the native rod outer segment disk membrane; however, at 37 degrees C, 40% of the photointermediates are in the form of meta II. The formation of meta II above Tm is slowed by a factor of ca. 2 relative to the disk membrane. Below Tm, the equilibrium is shifted still further toward meta I, and meta II forms ca. 7 times slower than in the disk membrane.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
9.
- Intracellular recording were obtained from P-cells of the LGN of the cat. The impulse trains of a single presynaptic retinal ganglion cell and the postsynaptic P-cell were separated by band-pass-filtering and subsequent amplitude discrimination.
- The rates of information and transinformation for the visual channel from the eye to a ganglion cell and to the connected P-cell were calculated. Input signals to the channel were trains of light flashes of different rate, luminance and spatial distribution.
- Transinformation was calculated without restrictive assumptions for the code.
- The transient behaviour of the system in response to a flash was fully considered for information calculations. Additionally, it was ensured that the state of the (adaptive) channel was considered correctly.
- Information theory was applied in an extended way. The time courses of information transfer were calculated for various flash stimuli and compared with each other.
10.
A. R. Bhatti 《Archives of microbiology》1974,96(1):255-266
- A hypothesis based on the Hill-Bendall-model of photosynthetic electron transport is proposed to explain positive and negative photo-phobotaxis inPhormidium uncinatum. In the non-cyclic electron chain a pool is located into which photosystem II (e. g. by absorption by C-phycoerythrin, 561 nm) feeds electrons while photosystem I (e.g. 723 nm) drains electrons out of it.
- Interruption of the electron flow into the pool causes a sudden decrease of the pool size and thus a positive phobic response. This happens e.g. when an organism leaves a trap which is illuminated by a wavelength absorbed by photosystem II pigments (e. g. 561 nm).
- A negative reaction takes place when electrons are suddenly drained out of the pool; again the pool size decreases. This is the case when an organism enters a light trap illuminated by photosystem I light (723 nm).
- The net flow of electrons into or out of the pool—and thus the reaction sense—can be manipulated by the relative excitation of the two photosystems or by blocking the electron influx by DCMU.
11.
Rowena G. Matthews Ruth Hubbard Paul K. Brown George Wald 《The Journal of general physiology》1963,47(2):215-240
Light isomerizes the chromophore of rhodopsin, 11-cis retinal (formerly retinene), to the all-trans configuration. This introduces a succession of unstable intermediates—pre-lumirhodopsin, lumirhodopsin, metarhodopsin —in which all-trans retinal is still attached to the chromophoric site on opsin. Finally, retinal is hydrolyzed from opsin. The present experiments show that metarhodopsin exists in two tautomeric forms, metarhodopsins I and II, with λmax 478 and 380 mµ. Metarhodopsin I appears first, then enters into equilibrium with metarhodopsin II. In this equilibrium, the proportion of metarhodopsin II is favored by higher temperature or pH, neutral salts, and glycerol. The change from metarhodopsin I to II involves the binding of a proton by a group with pK 6.4 (imidazole?), and a large increase of entropy. Metarhodopsin II has been confused earlier with the final mixture of all-trans retinal and opsin (λmax 387 mµ), which it resembles in spectrum. These two products are, however, readily distinguished experimentally. 相似文献
12.
Fast Electrical Potential from a Long-Lived,Long-Wavelength Photoproduct of Fly Visual Pigment
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A rapid electrical potential, which we have named the M-potential, can be obtained from the Drosophila eye using a high energy flash stimulus. The potential can be elicited from the normal fly, but it is especially prominent in the mutant norp AP12 (a phototransduction mutant), particularly if the eye color pigments are genetically removed from the eye. Several lines of evidence suggest that the M-potential arises from photoexcitation of long-lived metarhodopsin. Photoexcitation of rhodopsin does not produce a comparable potential. The spectral sensitivity of the M-potential peaks at about 575 nm. The M-potential pigment (metarhodopsin) can be shown to photoconvert back and forth with a "silent pigment(s)" absorbing maximally at about 485 nm. The silent pigment presumably is rhodopsin. These results support the recent spectrophotometric findings that dipteran metarhodopsin absorbs at much longer wavelengths than rhodopsin. The M-potential probably is related to the photoproduct component of the early receptor potential (ERP). Two major differences between the M-potential and the classical ERP are: (a) Drosophila rhodopsin does not produce a rapid photoresponse, and (b) an anesthetized or freshly sacrificed animal does not yield the M-potential. As in the case of the ERP, the M-potential appears to be a response associated with a particular state of the fly visual pigment. Therefore, it should be useful in in vivo investigations of the fly visual pigment, about which little is known. 相似文献
13.
Hydrogen ion changes of rhodopsin I. Proton uptake during the metarhodopsin I 478 metarhodopsin II 308 reaction 总被引:3,自引:0,他引:3
The hydrogen ion changes resulting from the photolysis of the rod visual pigment, rhodopsin, have been investigated. Low temperature was used to isolate the metarhodopsin I478 to II380 reaction of rhodopsin and indicator dye was used to simultaneously measure the hydrogen ion changes of the rhodopsin solution.The results indicate that illuminated rhodopsin takes up a proton during the metarhodopsin I478 to II380 reaction and releases protons at later intermediate stages. The results are consistent with data indicating pK changes of rhodopsin as the basis for the R2 phase of the early receptor potential and hydrogen ion changes of the medium or pK changes of rhodopsin as having effects on the late receptor potential. 相似文献
14.
M. Kawasaki 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,173(1):9-22
An African electric fish, Gymnarchus, and a South American electric fish, Eigenmannia, are believed to have evolved their electrosensory systems independently. Both fishes, nevertheless, gradually shift the frequency of electric organ discharge away when they encounter a neighbor of a similar discharge frequency. Computational algorithms employed by Gymnarchus for this jamming avoidance response have been identified in this study for comparison with those of extensively studied Eigenmannia.
- Gymnarchus determines whether it should raise or lower its discharge frequency based solely upon the signal mixture of its own reafferent and the exafferent signal from a neighbor, and does not internally refer to the pacemaker command signal which drives its own discharge.
- The signal mixture is analyzed in terms of the time courses of amplitude modulation and phase modulation at each area of the body surface.
- Phase of the signal mixture at each area is compared with that of another area for the detection of phase modulation.
- Unambiguous information necessary for the jamming avoidance response is extracted by integrating information from all body areas each of which yields ambiguous information.
- These computational features are identical to those of Eigenmannia, suggesting that the neural circuit for jamming avoidance responses may have evolved from preexisting mechanisms for electrolocation in both fishes.
15.
The rhodopsin system of the squid 总被引:6,自引:19,他引:6
Squid rhodopsin (λmax 493 mµ)—like vertebrate rhodopsins—contains a retinene chromophore linked to a protein, opsin. Light transforms rhodopsin to lumi- and metarhodopsin. However, whereas vertebrate metarhodopsin at physiological temperatures decomposes into retinene and opsin, squid metarhodopsin is stable. Light also converts squid metarhodopsin to rhodopsin. Rhodopsin is therefore regenerated from metarhodopsin in the light. Irradiation of rhodopsin or metarhodopsin produces a steady state by promoting the reactions, See PDF for Equation Squid rhodopsin contains neo-b (11-cis) retinene; metarhodopsin all-trans retinene. The interconversion of rhodopsin and metarhodopsin involves only the stereoisomerization of their chromophores. Squid metarhodopsin is a pH indicator, red (λmax 500 mµ) near neutrality, yellow (λmax 380 mµ) in alkaline solution. The two forms—acid and alkaline metarhodopsin—are interconverted according to the equation, Alkaline metarhodopsin + H+ acid metarhodopsin, with pK 7.7. In both forms, retinene is attached to opsin at the same site as in rhodopsin. However, metarhodopsin decomposes more readily than rhodopsin into retinene and opsin. The opsins apparently fit the shape of the neo-b chromophore. When light isomerizes the chromophore to the all-trans configuration, squid opsin accepts the all-trans chromophore, while vertebrate opsins do not and hence release all-trans retinene. Light triggers vision by affecting directly the shape of the retinene chromophore. This changes its relationship with opsin, so initiating a train of chemical reactions. 相似文献
16.
Reiko Hara 《The Journal of general physiology》1963,47(2):241-264
The change in electrical conductance of rhodopsin solutions was studied with flash-photolysis techniques. The whole pattern of the conductance change on illumination consists of three different processes: (I) the initial decrease, (II) the increase, and (III) the slow decrease, which are in decreasing order of reaction rate. The processes I, II, and III can be most distinctly recognized on flash illumination of acid, slightly acid, and alkaline rhodopsins, respectively. On the other hand, the bleaching of rhodopsin also shows at least three successive phases of different rates, but none of them corresponds in reaction rate to any of the processes of the conductance change. The conductance change may be related to conformational changes of opsin following photoisomerization of retinene, being due to hydrogen or hydroxyl ions and some other inorganic electrolytes. The amount of the change, especially the initial decrease, is proportional to the amount of rhodopsin bleached, even when the photochemical back reaction towards rhodopsin and isorhodopsin occurs in the chromophore depending on the intensity of illumination. Of the three processes, the slow decrease is most severely affected by aging, but the initial decrease and increase are slightly affected. These two processes promptly caused by illumination are connected closely to the conformational changes during the conversion of rhodopsin to metarhodopsin, and perhaps to the initial stage of excitation of rod cells. 相似文献
17.
The decay reactions of metarhodopsin II and the dissociation of the complex between rhodopsin (in the metarhodopsin II state) and the GTP-binding protein (G-protein) (in its inactive, GDP-binding form) have been compared at various concentrations of hydroxylamine. The reactions of the chromophore were measured by absorption changes in the visible range, the complex dissociation by changes in the near-in-frared scattering. An additional monitor of the complex was given by the G-protein-dependent equilibrium between metarhodopsin I and metarhodopsin II. For all measurements, fragments of isolated bovine rod outer segments in suspension were used. In the absence of hydroxylamine, the rhodopsin-G-protein complex dissociated within 20–30 min at room temperature. The presence of hydroxylamine greatly accelerated (e.g., 5-fold at 1 mM NH2OH) the dissociation. Under all conditions, the free, dissociated G-protein can reassociate to metarhodopsin II produced by subsequent bleaching. Dissociation of the metarhodopsin II-G-protein complex required the decay of photoproducts with a maximal absorbance of 380 nm, but was not affected by the simultaneous presence of metarhodopsin III or metarhodopsin III — like photoproducts with a maximal absorbance between 450 and 470 nm. Despite the acceleration of metarhodopsin II-G-protein dissociation by NH2OH, metarhodopsin II-G-protein was relatively stabilized as compared to free metarhodopsin II. The ratio of the decay rates of free metarhodopsin II and metarhodopsin III-G-protein was increased as much as 10-fold in the presence of 25 mM NH2OH. The results indicate a mutual interdependence of retinal, opsin and G-protein. 相似文献
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20.
M. V. Sergejeva A. V. Popov 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,174(3):381-389
- The ontogeny of positive phono taxis (PPT) in female crickets, Gryllus bimaculatus was followed in tethered flight. During the first day of adult life many females already demonstrated PPT to the calling song (CS) of conspecific males. The average threshold of PPT at 5 kHz, the dominant frequency of the CS, decreased by 30 dB by the time of sexual maturity (Fig. 1).
- No correlates of this decrease were found in the activity of the most sensitive ascending prothoracic neuron tuned to 5 kHz recorded in the neck connective. This is presumably the AN1 neuron which is known to be involved in PPT realization. Its threshold at 5 kHz in young animals was the same as in adults. Therefore, ascending circuits of PPT seem to be mature by the first day of imago life and there should be some other mechanisms preventing performance of PPT by young walking females until maturation.
- The PPT of females in flight is tuned to 5 kHz, much sharper than in walking (Fig. 2). In flight, the carrier frequency of a signal is probably an important parameter driving PPT, at least in a no-choice situation, whereas on the substrate, at close range, temporal parameters become decisive.
- The ontogenetic development of the selectivity of a female's PPT to temporal parameters of a signal passes 3 successive steps: 1) response mainly to the trill with pulse repetition rate as in the CS; 2) response mainly to the actual CS with chirp structure; 3) destruction of selectivity (Figs. 3–6). The existence of steps 1 and 2 strengthens our hypothesis, that in phylogeny, the trill (pulse rate) detector of the CS “recognizer” in the CNS appeared earlier, and was later accompanied by the chirp detector.
- Joint breeding of female larvae with males accelerates maturation of the CS recognizer.