ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06085.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Small amounts ofN‐methyl phenazonium methosulphate (PMS) added to a suspension ofChlorella pyrenoidosaaccelerate the emission of the long‐lived far‐red induced afterglow without greatly changing the amount of light emitted. The effect is noticeable in dilute suspensions at a PMS concentration of 10‐9M.The concept of afterglow unit is introduced and defined as that part of the sample in which the rate of energy reemission can be controlled by a single molecule of PMS. The number of chlorophyll molecules per afterglow unit is about 105. It is possible that the afterglow unit is identical to the thylakoid.The rate constant for the final first order decay phase of afterglow at room temperature is about 0.7 min‐1without PMS and about 3 times larger for a unit with one PMS molecule.Diuron (DCMU) lowers the rate of afterglow decay. Desaspidin on the other hand decreases the amount of light emitted without affecting the decay rate. Carbonylcyanide‐m‐chlorophenyl hydrazone (CCCP) decreases the afterglow over the whole time‐range and increases the decay rate. A kinetic model is developed to acco

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06086.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–The structure of a complex formed from retinaldehyde and ethanolamine phosphoglyceride has been proposed as a Schiff's base stabilized byπ–πinteraction between the double bond of an oleic acid group (Δ9) and the 9–10 double bond of the retinaldehyde chain. Considerations of stereochemistry and simple MO theory indicate the proposed structure to be energetically favored, and its absorption maximum is predicted by free elect

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06087.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Products of oxidation of β‐carotene, photosensitized by hypericin in acetone, appear to include mutatochrome, aurochrome, and a number of other compounds absorbing in the violet and near u.v. regions of the spectrum. The 5, 6‐monoepoxide is not formed in appreciable quantity, though it is the principal product of oxidation of carotene by perphthalate. Mutatochrome, lutein, and zeaxanthin are photooxidized more slowly than β‐carotene, and the products do not appear to include 5, 6‐epoxides. β‐carotene‐5, 6‐monoepoxide is oxidized to what is probably luteochrome. Quantum yields appear to be low. We found no evidence to support a photochemical contribution to the oxidation of zeaxanthin to violaxanthin, a process known to acco

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06088.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Fraction‐1 particles were prepared by passing spinach chloroplasts three times through the French pressure cell and centrifuging in a sucrose gradient.With the electron donor DAD (diaminodurol or 2,3,5,6‐tetramethyl‐p‐phenylenediamine) and ascorbate, a light‐induced difference spectrum revealed the oxidation of both cytochromefand P700 upon illumination of these particles. The oxidation of cytochromefwas completed in less than 0.5 msec. P700 and cytochromefthus seem to be tightly bound to each other in these particles. Addition of Triton X‐100 abolished the fast oxidation of cytochromefbut not that of P700.Artificial electron donors such as DAD, DCIP (2,6‐dichlorophenol indophenol), and PMS (N‐methylphenazonium methosulfate) were good electron donors for photoreaction 1 in these particles, while neither plastocyanin,Porphyracytochrome 553, norEuglenacytochrome‐552 reduced P700 efficiently. However, after treatment of fraction 1 particles with Triton X‐100 reduced DAD, DCIP and PMS were no longer efficient electron donors, while plastocyanin and the algal cytochromes were highly active in reducing P700. Mammalian cytochromecwas not a good electron donor either before or after Triton treatment.Measurements of the effectiveness of P700 reduction as a function of concentration in Triton‐treated particles showed plastocyanin to be about four times more active thanPorphyraorEuglenacytochromes which in turn were about fourteen times more active than mammalian cytochromec.Recent studies by Murata and Brown have shown that plastocyanin is not required for the reduction of NADP in these particles with DCIP and isoascorbate as electron donors. The present investigation and that of Murata and Brown indicate that disintegration of chloroplasts with the French pressure cell and centrifugation in a sucrose gradient is the best method to separate system‐1 particles having an electron‐transport system in almost the na

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06089.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Nicotiana tabacumvar.Xanthin.c. plants placed in the dark lose their ability to photoreactivate u.v.‐irradiated tobacco mosaic virus RNA over a course of approximately 1 week. When such plants are returned to the light, they recover their photoreactivation ability. The recovery occurs after a lag of at least 3 hr and is complete in 12–24 hr. Three hours or less of cool‐white illumination (2400 ft‐c) are necessary to induce recovery. Blue light is effective in inducing recovery; green light is less effective; red and near‐u.v. are

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06090.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Triplet states of several large polycyclic aromatic hydrocarbons together with their lifetimes have been determined both in fluid solution and in the solid state using a spectrophoto‐metric technique.Excited states and lifetimes of some solid charge transfer complexes between the hydrocarbons and chloranil have been examined.The assignment of the1Bbstates of some of the hydrocarbons have been made from the energies of the triplet s

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06091.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Photohemolysis of erythrocytes. from patients with erythropoietic protoporphyria results from damage to the cell membrane following photoexcitation of the protoporphyrin molecule by 400 nm radiation. Photochemical reactions were assessed for their roles in initiating cell destruction in anin vitromodel in which erythrocytes from patients with erythropoietic protoporphyria were irradiated. Electron transfer properties were demonstrated using 2,3,6‐trichloroindophenol as an electron acceptor. Photohemolysis of these abnormal cells is due to cell membrane damage initiating colloid osmotic hemolysis. Additional data are offered demonstrating that this type of photohemolysis is oxygen‐dependent, associated with peroxide formation, and preceded by increased osmotic fragility. An hypothesis explaining the interrelationship of the photochemistry of protoporphyrin with the photobiologic observation of hemolysis is

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06092.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06093.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The excision‐repair of damaged DNA in bacteria and other systems probably requires at least three enzymes to carry out the following steps in sequence: (1) Recognition of a structural distortion in the DNA and the production of an endonucleolytic cleavage of the damaged strand near the lesion. (2) The simultaneous peeling back of the damaged strand and resynthesis of the excised region, with eventual cleavage of the damaged segment from the DNA. (3) The rejoining of the newly synthesized strand to contiguous parental DNA. Evidence for all three steps has been obtained fromin vivostudies. TheE. coliDNA polymerase has been shown to carry out step # 2in vitro[1] and the polynucleotide ligase has the required specificity for step # 3[2–4]. An enzyme responsible for step # 1 has been purified fromMicrococcus lysodeikticus[5,6] but not fromE. coli, although a class of u.v. sensitive mutants inE. colihas been shown to be defective in this step in the repair sequence. In such mutants the release of pyrimidine dimers from the damaged DNA is not observed during post‐irradiation growth of u.v. irradiated cultures [7]. It would be predicted, as a consequence, that the next step, non‐conservative repair replication, would not be seen in these mutants. Hanawalt and Petti‐john showed this to be true for the double mutantE. coliB8‐1that includes a deficiency in dimer excision [8]. In the present study we have looked more closely at anE. coliK‐12 strain that has only theuvrA6deficiency that results in inability to excise pyri

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06094.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY