摘要:

Abstract—The photoreduction of viologens with NADPH as an electron donor was investigated. As the photosensitizer in that reaction, ZnTPP33‐and HmP were applied. HmP dissolved by CTAB or Triton X‐100 was a more active photosensitizer than ZnTPPS33‐. The reduction rate of viologen under steady state irradiation depends remarkably on the type of surfactant used for dissolving HmP. The effect of the surface charge of micelle was examined by laser flash pho

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05583.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—Photoaffinity labeling of synthetic DN As with ethidium monoazide was studied to determine if the efficiency of adduct formation was related to DNA sequence. Equilibrium drug binding to DNA homopolymers and copolymers was quanitified by phase partition techniques. The amount of drug bound to a deoxypolymer at equilibrium was then compared to the fraction of ethidium analog covalently‐linked following photoactivation at the same drug/DNA input ratio. There were significant sequence‐related differences in the ability of the photoaffinity probe to label DNA covalently. The efficiency of covalent‐adduct formation decreased in the order poly(dG‐dC).poly(dG‐dC)>poly‐(dG). poly(dC)poly(dA‐dT). poly(dA‐dT)poly(dA). poly(dT). Ethidium monoazide was about 2‐fold more efficient in labeling deoxyhomopolymers and deoxycopolymers composed of G‐C pairs than the A‐T base counterparts. In low ionic buffers (0.015MNa+), the efficiency of photoactivation decreased with increasing ethidium monoazide concentrations. However. the base sequence effect was observed over a 40‐fold range of drug concentrations. Therefore, the amount of ethidium monoazide bound to a DNA site after irradiation does not appear to represent the true affinity

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05584.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—Aqueous solutions of L‐tryptophan were photolyzed by exposure to 337.1 nm radiation from a pulsed nitrogen laser. These data were compared with results for the 290 nm conventional‐source photolysis of tryptophan. The progress of photolysis was monitored by fluorescence analysis of tryptophan. UV absorption spectroscopy, HPLC, TLC, and proton NMR spectroscopy. The loss of Trp was observed to be first order for 290 nm photolysis but of mixed order for 337.1 nm photolysis. Five photolysis products were detected by TLC analysis, including: N‐formylkynurenine. kynurenine, tryptamine (detected after 290 nm photolysis but not 337.1 nm photolysis) and two unknown products. The tryptophan‐containing peptides N‐acetyl‐tryptophanamide (NATA) and tryptophylglycine (Trp‐Gly) were also observed to photolyze upon 337.1 nm laser radiation demonstrating that this phenomenon is not restricted to free tryptophan monomer.Since Trp is not ordinarily thought to absorb U V radiation at wavelengths as long as 337.1 nm. a number of experiments were performed in an effort to determine the mechanism of photolysis at this wavelength. Evidence is presented which indicates that the 337.1 nm laser photolysis of Trp doesnotresult from two photon absorption, dielectric breakdown, or other laser‐specific processes. Instead. it is concluded that this photolysis results either from a very weak absorption tail extending to 337.1 nm in tryptophan itself or from a reaction involving an impurity sensitizer which absorbs the 337.1 nm radiation. The sensitizing impurity. if present, could not. however, be removed by preparative HPLC and could not be detected by TLC or fluo

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05585.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—Harmine, a β‐carboline alkaloid, was found to be an efficient photoactive agent against the DNA‐containing murine cytomegalovirus (MCMV) and the RNA containing Sindbis virus, a togavirus, both of which contain membranes. In contrast the host cells themselves were relatively resistant. The MCMV was investigated in more detail. Virus which had been inactivated by harmine plus UVA retained its structural integrity and was fully capable of penetrating host cells, following which the viral genome entered the cell nucleus. The viral genes which normally code for the switch‐off in thymidine kinase activity arid for the normal cytopathiceffectswere not expressed; however the viral geneis responsible for the cytotoxic effect due to high multiplicities of infection was still expressed, indicating that there may be a differential block of some vi

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05586.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—Murine cytomegalovirus, a herpes virus, was used as a model virus to investigate the mechanism of the anti‐viral action of phenylheptatriyne in long wave ultraviolet light. The genome and proteins of the inactivated virus penetrated the nuclei of susceptible cells normally. Furthermore, the viral genome did not contain extra single strand breaks or cross‐links. However, cells infected with the treated virus did not synthesize late viral proteins, as determined by polyacrylamide gel electrophoresis. nor did they synthesize late viral RNA and viral DNA according to nucleic acid hybridization tests. Thus the compound may interfere with an early viral function so that the replication cycle cannot pr

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05587.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—Herpes simplexvirus — type 1 (HSV‐I) plaque‐forming ability and plaque size were measured on C3H/1OT1/2 cell monolayers as functions of pretreatment dose with UV light at different times before inoculation with virus, in order to determine if UV‐enhanced reactivation (ER) of UV‐irradiated virus. as well as associated phenomena, could be obtained in this cell system. The number of virus plaques observed (i.e. the capacity of the cells to support virus growth) and the size of the plaques were found to increase substantially with pretreatment of the cells with UV light. However, no significant ER was observed. Therefore, the mechanisms responsible for the increases in plaque size and cell capacity seem to be independent of those responsible for ER. In work by others. C3H/l0T1/2 cells have hcen transformed by UV light at doses similar to those used in this study; the absence of ER of UV‐irradiated virus in this study indicates that the mechanism underlying ER is not required for t

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05588.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—The mouse Skh:HR‐2 has been reported to be sensitized to ultraviolet light and become pigmented. Using three independent parameters associated with pigmentation. we have examined the ability of the mouse to become pigmented. The methods utilized were spectroscopic (skin color). histological (melanocyte density and epidermal thickness), and biochemical (tyrosinase activity). Following a two‐week ultraviolet exposure, the mice were pigmented with the degree of pigment change related to the ultraviolet dose administered. Perturbations in skin color, epidermal thickness, melanocyte density, and tyrosinase activity were recorded. Mice were also examincd for their response to tyrosinc applied topically following each ultraviolet exposure. With the exccption of epidermal thickness. all the pigmentation parameters were accentuated when compared to results from ultraviolet exposure

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05589.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—A method for estimating the amount of pigment in normal human skinin uivois presented. This method is based on remittance spectroscopy. The spectrum of normal skin is compared to amelanotic skin and the logarithm of the ratio is fitted with a straight line in the range 620‐720 nm. The parameters obtained are strongly correlated for all the volunteers in this study. therefore each spectrum determines one parameter for each individual. When similar analysis was performed on DOPA‐melanin we obtained the same strong correlation among different concentrations. We are thus able to determine a relation between the coefficient obtained from the remittance spectrum from normal skin and an equivalent concentration of DOPA‐melanin in aqueous solution. We can thus estimate. to a first approximation, the total melanin mass in human skin non‐invasively, and can determine a parameter that is uniquely correlated to the amount of melanin pigment in

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05590.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—Kinetic resonance Raman (RR) experiments were designed to study the time‐behaviour of the retinal‐binding protein bacteriorhodopsin (BR) in its photochemical cycle. The unphotolyzed chro‐mophore B‐570 and the two intermediatesL‐550 andM‐412were probed by the characteristic C=C stretching vibrations of the retinal moiety. Time resolution was achieved with a spinning cell as flow system in combination with two CW lasers in a pump‐probe configuration. RR spectra were probed at 475 nm at various delay times between pump and probe event. The deconvolution of the spectra into the various components B‐570, L‐550 and M‐412 was carried out by curve fitting procedures. It was found that at pH7.4L‐550decays — with a time‐constant of 62 μs — not completely but to a residual level of 35% of its initial value. This intermediateL‐amplitude finally disappears in the ms‐range (4.5 ms) synchroneously with the intermediateM‐412. An analogeous time‐behaviour was found at pH 4.6. In the basic range also an “L” ‐intermediate could be identified which is coupled to the long‐lived M‐component. To explain the peculiar time‐dependence it is proposed that during the fast decay ofLa dynamic equilibrium betweenLandMis established. Then during the reconstitution ofB‐570 the two intermediates disappear synchroneously. A molecular model is presented in which the dynamic equilibrium betweenLandMis explained by an oscillatory motion of a proton from the Sc

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05591.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract—Propionibacterium acnes (P. acnes), grown on Eagles medium with different pH. were irradiated with monochromatic light in the range 320 to 440 nm. Different pH leads to different porphyrin concentrations in the cells. The light sensitivity of the bacteria was estimated from the reduction in their ability to form colonies after radiation. The sensitivity was highest for the lowest wavelength (320 nm). and decreased continuously with increasing wavelength up to 380 nm. In the region between 380 and 440 nm there was a second maximum (at 415 nm) which corresponds to the maximum absorption ol the fluorescing porphyrins inP. acnes. The sensitivity to 415 nm light was found to be dependent on the endogenous porphyrin concentration in the cells. while the sensitivity to 320 nm radiation was independent of the amount of porphyrin present. These results indicate that porphyrins produced by the bacteria are important for the light sensitivity of these bacteri

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1986.tb05592.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY