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1.
Nelson Durán Klaus Zinner Roberto Casadei de Baptista Carmen C. C. Vidigal Giuseppe Cilento 《Photochemistry and photobiology》1976,24(4):383-388
Abstract— The thiophenyl ester of indole-3-acetic acid and indole-3-acetonitrile produce chemiluminescence in aerated dimethylsulfoxide in the presence of potassium t -butoxide. The emitter is the aromatic aldehyde. In the case of acetonitrile, the other product expected from the cleavage of an intermediate dioxetane, cyanate/isocyanate, has also been identified. Other auxins also chemiluminesce under similar conditions, but the emitters have not been properly identified.
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
2.
Cornelia Bohne Adelaide Faljoni-Alario Giuseppe Cilento 《Photochemistry and photobiology》1988,48(3):341-347
Abstract— The interaction of serum albumin-bound acceptors with enzyme-generated and protected triplet species was studied in two types of systems. Chlorophyll-a bound to bovine and human serum albumins is efficiently excited by enzymatically generated triplet acetone and acetaldehyde. When the Chl-a concentration is much lower than that of the albumin the interaction occurs with chlorophyll in an aggregate in which one Chl-a is surrounded by several protein molecules. When the Chl-a concentration is higher than that of the protein, the aggregate contains the proteins and fluorescent chlorophylls in a 1:1 ratio. The excess chlorophylls, although able to interact with the donors, are not fluorescent.
In another study, probes bound to various specific sites of serum albumins were used as quenchers of the enzymatically generated triplet acetone. The efficiency of quenching by all the bound probes is equal and in one case even stronger than for the free probes.
A model for the interaction of the excited species contained in the enzyme with the acceptor(s) located in the protein is proposed.
The present results provide further evidence that enzyme-generated and protected triplet carbonyl species can interact through a collisional process with acceptors bound to or constituents of macromolecules. 相似文献
In another study, probes bound to various specific sites of serum albumins were used as quenchers of the enzymatically generated triplet acetone. The efficiency of quenching by all the bound probes is equal and in one case even stronger than for the free probes.
A model for the interaction of the excited species contained in the enzyme with the acceptor(s) located in the protein is proposed.
The present results provide further evidence that enzyme-generated and protected triplet carbonyl species can interact through a collisional process with acceptors bound to or constituents of macromolecules. 相似文献
3.
4.
PHOTOCHEMISTRY and PHOTOBIOLOGY WITHOUT LIGHT 总被引:3,自引:0,他引:3
Abstract— This review covers the literature since 1980 on chemically and enzymatically generated electronically excited species. The emphasis lies on triplet states of carbonyl products that are derived from dioxetanes and dioxetanones as precursors or from suitable enzymatic oxygenations. Singlet oxygen, an important excited state species in biological processes, is not explicitly treated. The utilization of triplet excited carbonyl products to promote photochemical and photobiological transformations by energy transfer are of primordial interest and not the photomechanistic behavior, photophysical properties and inherent photochemical reactions of such excited state species. Thus, the coverage concentrates on photodamage of DNA and RNA, the photochemistry of flavins, vitamin D, tryptophan, arachidonic acid, chlorophyll, lipid peroxidation, urocanase activation, excitation of chlorophlasts, and the aerobic oxidation of Schiff bases derived from amino acids and proteins. The potential perspectives of employing authentic dioxetanes and enzymatically generated dioxetane intermediates as effective photon equivalents in photochemotherapy, phototoxicity, photoaffinity labeling and photogenotoxicity are pointed out, in the hope of stimulating more intensive activity in this emerging and novel bioorganic and photobiological field. 相似文献
5.
Abstract— Enzyme-generated triplet species transfer energy very efficiently to thylakoid membrane fractions enriched in either photosystem-I or photosystem-II. Independent of the nature of the triplet donor, the emission is always more intense with photosystem-I. Since the fluorescence quantum yield of chlorophyll in PS-I is lower and the rate of energy transfer usually smaller than to chlorophyll in PS-II, the yield of 1 S chlorophylls in PS-I is substantially higher. This is tentatively attributed to more favorable reverse intersystem crossing from an upper triplet state in PS-I. 相似文献
6.
Isbli L. Nantes Giuseppe Cilento Etelvino J. H. Bechara Aníbal E. Vercesi† 《Photochemistry and photobiology》1995,62(3):522-527
Plant and animal mitochondria promote the aerobic oxidation of diphenylacetaldehyde (DPAA). This process is accompanied by chemiluminescence and rotenone-insensitive oxygen uptake. Tn rat liver and potato tubers, mitochondrial swelling is concurrently detected. Light emission and oxygen consumption decreased (about 50%) in cytochrome c-depleted mitochondria. A model system–cytochrome c or b5/dihexadecylphosphate liposomes–was also able to oxidize DPAA with parallel reduction of the cytochrome. Reduction of respiratory complex I or I plus II by addition of rotenone or antimycin A, respectively, did not prevent DPAA oxidation. However, when all cytochrome was reduced by addition of cyanide, aldehyde oxidation was completely suppressed. Altogether these data indicate that respiratory cytochromes are responsible for DPAA oxidation with production of excited species and consequent mitochondrial permeabilization. 相似文献
7.
LONG-RANGE TRIPLET-SINGLET ENERGY TRANSFER FROM ENZYME GENERATED TRIPLET ACETONE TO XANTHENE DYES 总被引:1,自引:0,他引:1
Enzyme-generated and protected acetone transfers its energy to xanthene dyes by a nontrivial process. The relative populations of the S1 state are indicative of the operation of a heavy atom effect, being 1:15:100 for fluorescein, eosine and Rose Bengal. On the other hand Stern-Volmer constants and k ET 0 values are similar for the three dyes and are remarkably higher than for collisional processes.
It is tentatively suggested that at least for eosine and Rose Bengal, a triplet-triplet cxciton transfer may occur to populate an upper triplet state of the dye followed by heavy-atom enhanced intersystem crossing to the S1 state. 相似文献
It is tentatively suggested that at least for eosine and Rose Bengal, a triplet-triplet cxciton transfer may occur to populate an upper triplet state of the dye followed by heavy-atom enhanced intersystem crossing to the S
8.
I. L. Brunetti E. J. H. Bechara G. Cilento E. H. White 《Photochemistry and photobiology》1982,36(2):245-249
Abstract In Colchicum autumnale L., colchicine is accompanied by its photoproducts, mainly β-lumicholchicine, even in parts not exposed to light such as the corm of plants grown in the dark. The transformation of colchicine into lumicolchicines can be efficiently accomplished in vitro by energy transfer from enzyme-generated triplet species to colchicine, thus providing additional evidence for'photobiochemistry without light'. 相似文献
9.
Edy Rivas-Suárez Luiz H. Catalani Etelvino J. H Bechara Giuseppe Cilento 《Photochemistry and photobiology》1983,37(1):93-97
Tyrosine and especially its 3,5-dihalogenoderivatives quench acetone triplets. When the excited acetone is generated free in solution, the Stern-Volmer plots for the quenching by these species, monitored via the sensitized emission of the 9,10-dibromoanthracene-2-sulfonate ion, are linear. When triplet acetone is generated enzymically by the peroxidase-catalyzed aerobic oxidation of isobutyral-dehyde, the Stern-Volmer plots for the quenching of the acetone phosphorescence curve upwards in the case of 3,5-dibromotyrosine and even more markedly with 3,5-diiodotyrosine. Quenching appears likely to occur by triplet-triplet energy transfer and especially in the case of the phenoxide form, also by electron transfer. The curvature denotes a static contribution to quenching favoured by the enzyme. 相似文献
10.
Abstract. The aerobic oxidation of saturated long chain fatty acids to the lower aldehyde and CO2 catalyzed by the α-oxidase system of young leaves from germinating Pisum sativum results in concomitant excitation of the chloroplasts or/and fractions present in the α-oxidase preparation. The excitation is attested to by both chlorophyll emission and Hill activity. This is the first case of photobiochemistry without light within a natural system. 相似文献