摘要:

Abstract—In polarotropism of the chloronema of the fernDryopteris filix‐mas(L.) Schott and of the germ tube of the liverwortSphaerocarpos donnelliiAust. a phytochrome action in blue and u.v. was presumed[1, 2]. In the present paper this assumption was tested by simultaneously irradiating with red and blue, and red and near u.v. Red energy is given to shift the phytochrome photoequilibrium in favour of highPfr/Ptotalconcentrations. The data obtained by simultaneous irradiation are consistent with the predictions made under the assumption of a phytochrome involvement in the blue‐ and u.v.‐mediated polarotropic r

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06048.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Egg white lysozyme was inactivated by photodynamic treatment in sodium phosphate buffer at pH8 using methylene blue, eosin Y and FMN as sensitizers. Measurements sensitive to changes in protein conformation, in particular, tryptophyl fluorescence and protease digestibility, were made during the course of inactivation. The rate of change of lysozyme tertiary structure as measured in these ways correlated closely with the rate of loss of enzyme activity during photodynamic treatment. Further, forms of lysozyme which were enzymatically active, but which were more sensitive to high temperature than native enzyme were produced by photodynamic treatment. It is concluded that the photodynamic inactivation of lysozyme under the conditions used results largely from the photooxidation of amino acid residues essential for the maintenance of the catalytically active conformation of the enzym

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06049.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—An action spectrum was obtained for photoreactivation of killing (PR) ofStreptomyces griseusconidia. This spectrum shows a major peak around 436 nm, originally observed by A. Kelner, and a secondary peak at 313 nm not previously reported. The rate of PR shows a strong dependence upon temperature and dose rate of the PR light at 436 nm, but this decreases to only a slight dependence upon these parameters at 313 nm. These findings suggested that PR at 436 nm in this organism is of the usual photoenzymatic type, but that PR at 313 nm might be of a different kind.A mutant (PHR‐1) ofS. griseuswas found that shows only a narrow range of PR (roughly 310–400 nm) with a single peak at 313 nm. The PR efficiency was lower than for wild type and the PR sector not greater than one‐half that of wild type. This PR shows no temperature dependence. Essentially similar behavior was observed with wild‐typeStreptomyces coelicolor.These findings show that at least some of the PR at 313 nm is a separable phenomenon. It is therefore unlikely to involve a mechanism identical to that at 436 nm.The nature of PR at 313 nm inStreptomycesis not known. If it is enzymatic, it is remarkable in having little or no dependence upon temperature and dose rate. Absence of photoprotection and liquid‐holding recovery indicate that it is not indirect PR. Some of it (that part exhibited byS. griseusPHR‐1 andS. coelicolor) might result from a direct photochemical

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06050.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Luminescence ofChlorellacells has been measured after illumination by a series of short saturating flashes.The intensity of luminescence is strongly dependent upon the number of flashes; luminescence is minimum after a single flash and maximum after a double flash illumination.Ifl/nis the intensity of luminescence measured 0.24 sec after the nth flash, the serieslnshows oscillations as a function ofn.The serieslnis very similar to the seriesyn, in whichyis the amount of oxygen evolved by the nth flash, the termlncorresponding to the termyn+1. To interpret the oscillations of the seriesyn, different models of system II photochemical centers have been proposed, one by ourselves and the other one by KOKet al.In these models the electron donorZof photosystem 11 is supposed to have 2 or 4 levels of oxidation, the more oxidized state being the precursor of oxygen. These different oxidation states of the donorZallow storage of the photic energy in the system. The correlation between the seriesynandlnshows that at least one of the oxidized forms of the donorZis a substrate for the luminescence reactio

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06051.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—U.V.‐irradiation of phageT4Borresults in a decrease in sedimentation rate of BU‐DNA which is attributed to single‐ and double‐strand breaks. No breaks could be observed in unsubstituted DNA. Cysteamine present during u.v.‐irradiation is able to prevent double‐strand breaks but does not influence the production of single‐strand breaks measured by alkaline sucrose gradient centrifugation. The biological importance and nature of DNA strand breaks due to BU‐incorporation as well as the action of the protective agent on these breaks and on the biological activ

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06052.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The gas phase photochemical reactions of SO2induced by 3130 Å radiation have been studied in the presence of added alkanes or added CO. The quantum yields obtained in the reactions with the low molecular weight alkanes employed are lower than those obtained by previous workers. The quantum yields were found to be pressure dependent increasing slowly with increasing pressure. A stoichiometric ratio of one SO2removed per molecule of hydrocarbon consumed was observed only under experimental conditions of [SO2]<[RH]. For reaction mixtures where [SO2]<[RH] the ratio of [SO2]/[RH]reacted always exceeded unity. The quantum yields decreased slightly with increasing temperature. In all the alkane reaction systems studied, the deposition of viscous, nonvolatile reaction products was observed. In the experiments with added CO, the quantum yields were computed with respect to the rate of CO2formation. At 25°C and equal pressures of SO2and CO, φco2was observed to be 0.005 and it decreased slightly with increasing temperature. The results obtained are interpreted in terms of the sulfoxidation of the alkanes and the oxidation of CO proceeding by way of a3SO2reaction intermed

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06053.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—A study was made of the kinetics of the proflavine‐sensitized photooxidation of methionine to methionine sulfoxide. The reaction is inhibited by the paramagnetic ions Cu2+and Mn2+, which suggests that the triplet state of the sensitizer is an intermediate. A mechanism is proposed in which methionine reacts with the first singlet state of oxygen, produced by energy transfer from the triplet sensitizer. The decrease in the rate of photooxidation with increasing proflavine concentration is ascribed to self‐quenching of the excited singlet state of th

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06054.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06055.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb06056.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY