摘要:

Abstract—The photoreactions of isorhodopsin, a synthetic visual pigment containing 9‐cis retinal, were studied between –45° and –75°C using flash photolysis. Light‐induced absorbancy changes were observed which were indistinguishable from those caused by the photo‐production of prelumirhodopsin from the natural visual pigment rhodopsin. It is concluded that isorhodopsin is converted to prelumirhodopsin although less efficiently than is the natural pigment. Thermally unstable intennediates of bleaching are also converted to pre‐lumirhodop‐sin by light, possibly by way of rhodopsi

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08020.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—When bleached, aerobically grown cells ofRhodopseudomonas spheroidesare transferred to semi‐aerobic conditions to induce bacteriochlorophyll synthesis, a new fluorescence band, with a maximum at 790 nm, is observed in addition to the 885 nm emission maximum normally seen in pigmented cells. The 790 nm fluorescence may be due to bacterio‐chlorophyll which has not been bound into the chromatophore membrane. The quantum yield of the 885 nm fluorescence is at first relatively high and then, about 1 hour after transfer, drops to the level found in pigmented photosynthetic cells. The coupling to the rest of the photo‐synthetic apparatus, as indicated by the effect of dithionite on the fluorescence, also seems to occur during the first hour of pigment development, which suggests that the onset of fluorescence quenching is due at least in part to the synthesis of photochemical reaction centers. Continuation of these studies should provide new information on the formation, structure and molecular interactions of the pigments and the photosynthetic me

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08021.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Various organic solutions were irradiated in a search for rapidly reversible EPR photosignals. Using an averaging technique, the rise and decay of the photosignals of CT‐complexes formed between chloranil and organic solvents were shown to be of the order of tens of msec. However, the mechanism involved could not be fully elucidated without additional data such as those obtained from flash photolysis and other techniq

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08022.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Neutral, acidic or basic frozen aqueous solutions of aromatic amino acids undergo photoionisation under u.v. irradiation, at 77°K. In neutral or basic solutions, photo‐ejected electrons are trapped in the solvent matrix and exhibit a characteristic absorption band in the visible region. In acidic solutions electrons are trapped by protons and ESR signal spectrum of hydrogen atoms may be observed. Hydrogen atoms are also produced in low yield in neutral or basic frozen aqueous solutions, u.v. irradiated at 77°K. In basic media the ESR spectrum of 0‐radical ions is observed. Kinetic studies as a function of light intensity show that photoionisation takes place after absorption of a second photon by the phosphorescent molecule in its lowest triplet state. Recombination of trapped electrons in neutral or basic solutions may be induced using secondary excitation with visible light. In all instances we could record the absorption spectrum of photolytic products of aromatic amino acids and polypeptides which are u.v. irradiated

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08023.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The correction factors due to the overlap of absorption and emission spectra have been calculated for various concentrations of fluorescein dye at pH 12 by using the experimentally obtained value of apparent molar absorptivity, ε2, for the fluorescence radiation. The observed fluorescence intensities for the same‐surface detection for a given geometry have been corrected for the secondary emission effect thus calculated, and also for refraction and dilution effects, to give corrected relative quantum yields for the solutions. These have been converted to the absolute values by comparison of the integrated fluorescence quantum spectrum of a dilute solution of fluorescein with that for quinine sulphate in 0.1 N H2SO4. The corrected quantum yields compare well with values given in the litera

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08024.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—In isolated spinach chloroplasts, the reduction of cytochrome b‐559 by System II and its oxidation by System I can be observed when electron acceptor concentration limits System I activity and when one of a particular class of uncoupling agents is present. This class includes CCCP, desaspidin, Triton X‐100 and antimycinA; but not simple amines or atebrin.The effect of the uncoupler is to speed the cytochrome b‐559 oxidation rate. In addition, the rate of the off‐response of the light‐induced P518 absorbance change is increased. To explain these findings, an electron transfer scheme is proposed having two distinct pathways between System II a

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08025.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Flash‐photolysis of safranine in deoxygenated 5 per cent aqueous pyridine produces a transient bleaching, which disappears by a second order process. Very probably this transient species consists of a pair of radicals or radical ions and not of the safranine in the triplet state. These radicals are also produced in chlorophyll sensitized reactions. Present results combined with previous work by us[I] indicate that the chlorophyll sensitization of safranine bleaching involves the formation of these radicals.The direct photochemical reduction of safranine to its leuco form occurs through the intermediate formation of the radicals. The appearance and disappearance of these radicals is fast compared to the role of photochemical formation and thermal disappearance of leuco safranine. Ascorbic acid influences but is not essential to the photo‐bleaching of safranine in 5 per cent aqueous pyridine. An increase in ascorbic acid concentration increases the steady‐state yield of the radicals but decreases the steady‐state yield of the leuco safranine. In the absence of ascorbic acid or other added substance, safranine photobleaches irreversibly in deoxygenated 5 per cent aqueous pyridine. A plausible mechanism is proposed in explanation of the direct photochemical reduction of

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08026.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The wavelengths most active in influencing the growth of segments of oat mesocotyl are 435 nm (blue), 665 nm (red) and 730 nm (far red). Using a high‐energy source (1.5 × 1018quanta/cm2), an inhibition in all areas of the spectrum except the far red was obtained. The efficiency of the different radiations was studied: blue light is the most active, red and far red have about the same efficiency; green is a thousand times less active. The effect induced by blue light cannot be directly attributed to phytochrome, because the wavelength of maximum effect does not correspond with that of maximum absorption of the pigment (there is 55 nm difference); also, blue light is more active than the red radia

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08027.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08028.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1968.tb08029.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY