摘要:

Abstract—On irradiation of all‐trans5,6‐dihydroretinal (I), two opsin‐active isomers are formed. Both these isomers (believed to be the 11‐cisand 9‐cisisomers) individually couple with cattle opsin to form complexes which have maximal absorption at 465 nm. These complexes satisfy all the established criteria characteristic of synthetic visu

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05711.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.tb05712.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The triplet states of some acridine dyes (proflavine, acriflavine, acridine yellow, acridine orange, ethacridine (Rivanol), benzoflavine), dissolved in a dimethylformamide/water matrix were investigated at 90°K by ESR. Zero‐field splitting parameters were calculated from the ESR spectra. The relationship between the zero‐field splitting and the distribution of the spin‐density of the electrons of the triplet state of the acridine derivatives is d

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05713.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Among the natural or synthetic furocoumarins (psoralens) a group exists which has interesting biological properties, the best known of which is skin‐photosensitization. The mechanism of action has remained unclarified for a long time. Furocoumarins lack photooxidative properties; they act by a mechanism that does not require oxygen and are therefore different from photodynamic substances. Photosensitizing furocoumarins when irradiated at 365 nm react with nucleic acids to give a C4‐cyclo‐addition to the 5,6‐double bond of the pyrimidine bases engaging their 3,4‐ or 4‵,5‵‐double bond. Differences exist in the behaviour of the various furocoumarins; psoralen reacts equally well with native DNA, with denatured DNA and with RNA, whereas bergapten, xanthotoxin and 8‐methylpsoralen at room temperature react to a much greater extent with native DNA than with denatured DNA and with RNA. A temperature effect has also been observed. In the case of native DNA an intercalation, occurring in the dark, of furocoumarins between two adjacent base pairs of the double helix is suggested as the first step in the reaction. The photoreaction is not accompanied by breaks in the polynucleotide chain or by conformational modifications of the macromolecule. A parallelism was observed between the order of activity of the substances of this group for photoreaction with native DNA and for skin‐photosensitization. Ehrlich ascites tumor cells lose completely their capacity of transmitting the tumor after irradiation in the presence of psoralen, bergapten and xanthotoxin. By hydrolysis of DNA extracted from Ehrlich ascites tumor cells irradiated in the presence of psoralen a photoadduct between psoralen and

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05714.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Recovery from sublethal damage by u.v. irradiation as measured by the split‐dose technique was investigated in stationary phase populations of diploid yeast Saccharomyces cerevisiae. Ft has been found that only about 35 per cent of the irradiated population is able to undergo recovery before the first subsequent cell division. The qualitative pattern is not changed if maximum photoreactivation is allowed after the first dose. Measurements of the decay of photoreactibility show that primary photo‐products are still present up to six hours after irradi

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1970.tb05715.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.tb05716.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.tb05717.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.tb05718.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY