摘要:

AbstractEquations are proposed for the estimation of quantum yields for cystine destruction and disulfide protein inactivation during u.v.‐irradiation in acidic and neutral solutions. The formulas permit a discussion of energy transfer from excited aromatic amino acids to cystines and/or of chemical reactions between excited tryptophans or tyrosines and cystines. The results are discussed with regard to general aspects of the photo‐biochemistry of enzy

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08743.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08744.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractPrevious work had shown that the rate of DNA syntheses in mammalian cells could be reduced when a microbeam of ultraviolet light was directed into the medium surrounding the cells. The present work was designed to gather informtion on the mechanism of this effect.Results show that catalase does protect the cellualar DNA synthesis under the following conditions.(1) The microbeam must be directed into the surrounding medium—there is no protection if it strikes any part of the cell.(2) The catalase must have been in contact with the cells for at least 4 hr before irradiation.(3) At high closes of radiation the protection is only partial.The catalase was labelled with fluorescent dye to demonstrate that it was able to penetrate the cell cytoplasm but not nucleus. Morphological studies on cell exposed to medium containing hydrogen pereoxide showed that protection was provided by intracellular and not extracellular catalasse and supported the idea that the toxic product produced by ultraviolet radiation of the medium was ultimately a peroxid

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08745.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

AbstractA mathematical formulation of the Kinetics of dimner and hydrate formation in pyrimidine dinucleosides upon ultraviolet (u.v.) radiatin is presented. The formulation allows for the possibilities of forming a number of types of dimers each with different cross sections for formtion and reversal, and of forming photo‐irreversible products such as hydrates. The general differential equations descrbinjg the kinetics are solved in terms of a series of exponential terms which are functions ofallthe cross sections. The way in which any given species of hotoproduct is dependent upon the cross sections is illustrted in several examples. The results have been used to predict the maximum amount of dirner which may be produced for a given set of cross sections and the exposure at which this maximum is expected. The conditions under which dimers may be detected in a mixture of parent and dimer upon re‐irradiation at short wavelengths are examined in terms of the differential equati

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08746.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Abstract‐Violet and ultravioet radiation are equally efficient in phot‐dimerizing aplhanathoquinone in benzene. The reactants yielding the dimeric photo‐product are moelcules in the ground state and excited ones. The photo‐reduction in 2‐propanol occurs with the same effciency for excitation in the n→* and →π* absorption bands. It is concluded that either reaction occurs via an n,π* excited state molecule, by direct excitation or after 100 per cent effucient internal conversion from the π,π*

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08747.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Abstract‐Lumichrome and other flavins were found to undergo a hydroxylation in the aromatic nucleus on irradiation with visible light under anaerobic conditions at low pH's. Arguments are given that the first step is the first step is the addition of water to the flavin in its excited stat

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08748.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08749.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08750.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08751.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1967.tb08752.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY