摘要:

Abstract—The quantitative changes in the levels of RNA and DNA in shoots treated with red and/or far‐red light are presented.The results indicate that red light, but not far‐red light, stimulated cell division. The changes in RNA are discussed in relation to the nature of the light trea

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05719.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract—The interpretation of the viscosity dependence of anthracene triplet decay is shown to be complexed by the effects of the macroscopic and the microscopic viscosity of the system on the translational diffusion coefficient. The second order rate constant for the decay of the anthracene triplet as measured by flash photolysis is equal to 2.45plusmn;.30×1091. mole‐1sec‐1for nearly a one hundredfold change in the viscosity of cyclohexane‐polyisobutylene solutions. The translational diffusion coefficient is unaffected by the presence of the polymer, and the local viscosity of the polymer solutions is identical to that of the pure

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05720.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract—The kinetics of the flavin‐sensitized photoinactivation of trypsin were investigated. Essentially similar results were obtained with riboflavin and with riboflavin‐5′‐phosphate (FMN) as sensitizers, while flavin‐adenine dinucleotide had only a very small sensitizing effect. The rate of the inactivation reaction was found to be directly proportional to light intensity over the range examined. The time‐course of the trypsin inactivation as measured by three assays could be fitted to first‐order kinetics.The rate of trypsin inactivation was identical as measured by the casein and benzoylargi‐nine ethyl ester assays, while a more rapid rate was observed as measured by the hemoglobin assay. These results are interpreted by postulating the existence of a “damaged” class of molecules after illumination uhich appears to be labile to post‐illumination heating or to 5Murea.Thet37value for trypsin inactivation, as corrected for the fraction of light absorbed, increased linearly with dye concentration. The trypsin concentration dependence of the reaction was found to be different in acid and basic solution. Trypsin had an inhibitory effect on the rate of photobleaching of the dye. Our results do not conform fully with any one of the several mechanisms that have been proposed to expl

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05721.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract—Some physical and photochemical properties of a proteinxhlorophyll complex which can be extracted from spinach chloroplasts with dilute Triton X‐100, have been measured. The molar extinction coefficient at the red maximum (671mμ) is 6.8 × 104. Solutions of the complex are weakly fluorescent, having a quantum yield of about 0.01. The complex undergoes photoautooxidation in the presence of oxygen with a quantum yield of about 0.2 × 10‐‐4, and sensitizes the autooxidation ofp‐toluene‐diamine (quantum yield about 1×10‐‐3) and of ascorbic acid (quantum yield 0.25). The complex‐catalyzed reduction of ferricyanide, in the presence of a protein‐carotene complex, was confirmed; its quantum yield is about 8 × 10‐‐4. The protein‐chlorophyll complex does not undergo a Krasnovsky reaction, nor could sensitized reductions of dye by abscorbate be detected. When excess Triton is added to the protein‐chlorophyll complex, it is converted into a detergent colloid apparently identical to a previously described Tween colloid.The properties of the protein‐chlorophyll complex are compared with those of other state

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05722.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05723.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract—The rate of photodynamic degradation of deoxy‐nucleic acids of various origins was followed by noting changes in their melting curves. The rate of degradation was proportional to the mole fraction of guanine residues in the nucleic acids, except for T4r+bacteriophage DNA which showed greater susceptibility than this rule would predict. The ability of dyes to act as sensitizers is correlated with their ability to form dye molecules in a metastable excited state. In addition, the binding of dyes to specific sites on the nucleic acid molecule was shown to be of great importance. Biological activity is a much more sensitive indicator of structural integrity of DNA than is the melting cu

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05724.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract—As previously demonstrated, there is a considerable increase in the photodynamic activity of anthraquinone‐sulphonic acid on the addition of ethylene glycol, glycerol and sugars in concentrations of the order of 0.4M. This system exhibits cytostatic activity. With H2O2at higher concentrations there is also formation of aldehydes in approximately equivalent yields as follows:R.CH2OH+Q → QH2+R.CHOQH2+O2→ Q+H2O2In accordance with the recent results of Warburg this accounts for the fundamental importance of glyceraldehyde in cancer research.Our results on the irradiation of Proteus vulgaris SG2 in buffered medium with the addition of glycerin to anthraquinone‐sulphonic acid show the existence of a similar cytostatic effect. One hour's irradiation with visible light reduces the cell count by about 50

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05725.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract—Exposure of the thymine requiring bacterium Escherichia coli strain B3 to ultraviolet light (u.v.) prior to incubation in the absence of thymine shortens the lag period normally observed before the onset of death due to lack of thymine. Culture conditions promoting synthesis of new kinds of enzymes at the time of thymineless challenge after u.v. irradiation enhance this effect. The effect can be reversed either by the addition of thymine or photo‐reactivation. Possible mechanisms for these phenomena are discus

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05726.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05727.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1965.tb05728.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY