摘要:

Abstract—The absorption and fluorescence spectra of chlorophylla(Chia)aggregates formed in aqueous solutions of polyvinyl alcohol) (PVA), polyvinyl pyrrolidone) (PVP), and bovine serum albumin (BSA) were analyzed by curve‐fitting methods in the wavelength region from 650 to 800 nm. The results indicated that the aggregation of Chiato polymeric forms such as (Chia–2H20), was suppressed in the presence of the macromolecules. The suppression was due to a coordination of macromolecule bound ligands to Chiaand was strongest in BSA and weaker in PVA. There were differences in the spectra even though the same types of polymeric Chiaforms were observed due to characteristically different composition of these forms. Fluorescence patterns indicated that energy was transferred from the shorter to the longer wavelength

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02887.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The emitting chromophores, emitting states, state orderings and phosphorescence lifetimes of neutral, hydrogen‐bonded, and protonated dibucaines in water/alcohol mixtures were determined experimentally and were confirmed theoretically using a HAM/3 method. These photophysical properties are used to probe the deprotonation dynamics of dibucaine‐HCl in the water/hydrophobic media. It is found that the protonated dibucaine in an aqueous solution is deprotonated and/or forms hydrogen‐bonded dibucaine when it is brought into contact with the alcohols and surfactants. The observed deprotonation processes could lend some insight on the molecular basis of pharmacological action of di

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02888.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—Photodynamic and biophysical properties of three porphyrin dimers joined by methylene bridges were examined. Fluorescence emission spectra and fluorescence lifetimes of the methylene‐linked dimers were similar to values obtained with porphyrin monomers. Singlet oxygen quantum yields were not significantly different when the three diporphyrins were compared. The diporphyrins were short‐acting tumor photosensitizersin vivo,and were rapidly cleared from plasma. Of the 3 diporphyrins examined, one was essentially ineffective as a sensitizerin vivo.This could not have been predicted fromin vitrostudies which indicated photodamage to membrane and mitochondrial loci. The methyiene‐linked diporphyrins were hydrophilic dyes (water/octanol distribution ratio =120–200) and bound mainly to plasma high‐density lipoprotein. In contrast, the more hydrophobic diporphyrin ester/ether fraction from HPD was a long‐persisting photosensitizerin vivo.Compared with hematoporphyrin, this hematoporphyrin derivative (HPD) fraction demonstrated a red‐shift in fluorescence emission and a shortened fluorescence lifetime. These comparisons suggest that ring‐ring interactions occur in the ester/ether‐linked diporphyrins from HPD, but not in the methyiene

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02889.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—After a preculture in white light,Acetabularia mediterraneaLamouroux (=A. acetabulum(L.) Silva) was irradiated with either continuous red or blue light. In crude extracts, the specific activities of UDPG pyrophosphorylase(uridine–5′‐triphosphate: glucose 1‐phosphate uridylyltransfer‐ase EC 2.7.7.9) and pyruvate kinase(adenosine–5′‐triphosphate: pyruvate phosphotransferase EC 2.7.1.40) varied as a result of the different light qualities. In red light activities decreased to 40% and 60%, respectively, within 3 weeks of irradiation, while under blue light, if not preceded by a red irradiation, the activities remained unchanged. After prolonged red light, high enzyme activities were restored by blue light with a relatively rapid time course (3 to 4 days for completion) compared with the decrease in red light. A fluence‐response curve for the activation of UDPG pyrophosphorylase showed two phases with different sensitivities for blue light.The blue light‐mediated increase in the activities of both enzymes was unaffected when the cell nucleus was removed before the beginning of the blue irradiation. The increase was inhibited by cycloheximide but not by chloramphenicol. Thus, functional cytosolic translation but notde novotranscription products are presumed to be required for the increase in specific enz

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02890.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—During prolonged continuous irradiation with red light the specific activity of uridine 5′‐diphosphoglucose (UDPG) pyrophosphorylase (uridine 5′‐triphosphate: glucose 1‐phosphate uridylyl‐transferase EC 2.7.7.9) decreased inAcetabularia mediterraneaLamouroux(=A. acetabulum(L.) Silva). Subsequent blue light restored the original activity within a comparatively short period of 3 to 4 days. Computer‐aided quantitative evaluation of density labelling experiments showed that the synthesis of the enzyme was accelerated about four‐fold during the period of activation by blue light. A similar increase in the rate of synthesis was found for hydroxypyruvate reductase (EC 1.1.1.81), a control enzyme that showed no blue light‐dependent changes in the specific activity under these conditions. The increase in the rate of enzyme synthesis was caused by an overall stimulation of the cytosolic translation. Degradation of UDPG pyrophosphorylase was unaffected by blue light, while the half life of hydroxypyruvate reductase was shortened about two‐fold compared to continuous red light. Thus, degradation of proteins appears to be selectively light dependent inAcetabularia.Model calculations for enzyme amount and enzyme synthesis were carried out using the measurements of enzyme activity, rates of cytosolic protein synthesis, and degradation constants of the enzymes. Assuming that activities represented amounts of the given enzymes, these calculations indicated a selective activation of UDPG pyrophosphorylase synthesis by blue light since it did not coincide with the overall stimulation of protein synthesis in the cytosol, in contrast to hydr

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02891.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—In the photoactivation of sulfite‐modified urocanase fromPseudomonas putida,the sulfite adds to the nicotinamide adenine dinucleotide and photodissociation accompanies activation. Bovine urocanase contains the same coenzyme. The purpose was to find if sulfite can inactivate a mammalian urocanase and if UV light can reactivate the enzyme. It was inactivated by sulfite,10–100i.M,and dialysis did not restore activity. Near‐UV light (11 W m‐2) reactivated the enzyme in 45 min. A competitive inhibitor protected urocanase from sulfite, showing that sulfite acts at the active site. The modification was dependent on temperature, time, and concentration of sulfite. The modification was reversed by incubation at 25°C for 24 h. These results resemble those found with theP. putidaurocanase. It is likely that these thermal‐ and photo‐reactions are the same for the bacterial and mammal

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02892.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02893.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02894.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02895.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb02896.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY