scholarly journals Flavin-photosensitized reactions of retinal and stilbene

1970 ◽  
Vol 120 (4) ◽  
pp. 673-681 ◽  
Author(s):  
Ann Gordon-Walker ◽  
G. K. Radda
Keyword(s):  
Triplet State ◽  
Diethyl Ether ◽  
Potassium Iodide ◽  
Substrate Concentration ◽  
Transition Energies ◽  
Photostationary State ◽  
Rate Of Reaction ◽  
Paramagnetic Ions

1. Retinol and stilbene are both isomerized when they are illuminated anaerobically in the presence of flavins. 2. Triplet quenchers (e.g. oxygen, potassium iodide and paramagnetic ions) inhibit the reaction more efficiently than they quench flavin fluorescence. At 77°C in a diethyl ether–isopentane–ethanol (5:5:2) glass retinol quenches flavin phosphorescence, but not its fluorescence. 3. For the stilbene reaction cis/trans photostationary-state mixtures are obtained with different flavins and these are linearly related to the phosphorescence transition energies of the flavins used. 4. The reaction involves the triplet state of flavin and a scheme for the reaction is suggested. 5. The dependence of the rate of reaction on substrate concentration is explicable in terms of this scheme. 6. The photobleaching of rhodopsin sensitized by flavin is also demonstrated.

Triplet‐State Quenching by Paramagnetic Ions in a Rigid Glass

1965 ◽  
Vol 42 (7) ◽  
pp. 2608-2608 ◽  
Author(s):  
B. Smaller ◽  
E. C. Avery ◽  
J. R. Remko
Keyword(s):  
Triplet State ◽  
Paramagnetic Ions

ESTIMATION OF MARSUPIAL RENIN USING MARSUPIAL RENIN-SUBSTRATE

1972 ◽  
Vol 53 (1) ◽  
pp. 125-130 ◽  
Author(s):  
PAMELA A. SIMPSON ◽  
J. R. BLAIR-WEST
Keyword(s):  
Substrate Concentration ◽  
Structural Difference ◽  
Plasma Renin ◽  
Angiotensin I ◽  
Ph Optimum ◽  
Ph Profile ◽  
Renin Substrate ◽  
Grey Kangaroo ◽  
Rate Of Reaction ◽  
Highly Correlated

SUMMARY Bilateral nephrectomy of an Eastern Grey kangaroo (Macropus giganteus) increased plasma renin-substrate concentration approximately tenfold when compared with intact kangaroos. A preparation made from this plasma had a renin-substrate concentration of 3000 ng/ml. A pH profile of rate of reaction with pig renin had an optimum at pH 5·39. By comparison, the pH optimum of sheep renin-substrate was pH 6·15. Estimates of plasma renin concentration for kangaroos, wombats and wallabies, using kangaroo renin-substrate or sheep renin-substrate were highly correlated. Results from incubation with sheep renin-substrate were greater and hence indicate the advantage in using this substrate for marsupial renin estimation. The consistently large difference between sheep and kangaroo renin-substrate when incubated with renin from marsupial and eutherian species appears to be due to a structural difference between the two substrates, probably near the C-terminal end of the angiotensin I molecule.

Photochemical reactions of charge-transfer complexes. The irradiation of the charge-transfer complexes between 1,4-, 1,5-, and 2,3-dimethoxynaphthalenes and 1,2-dicyanoethylenes

1980 ◽  
Vol 58 (9) ◽  
pp. 918-927 ◽  
Author(s):  
P. C. Wong ◽  
D. R. Arnold
Keyword(s):  
Charge Transfer ◽  
Triplet State ◽  
Ion Pair ◽  
Photochemical Reactions ◽  
Association Constants ◽  
Charge Transfer Complexes ◽  
Polar Solvents ◽  
Photostationary State ◽  
Ct Complex ◽  
Ct Complexes

The first part of this paper describes the experimental search for a donor which would complex preferentially one of the isomers of 1,2-dicyanoethylene. This involved measuring the association constants (KcDA) of the charge-transfer (ct) complexes of several dimethoxynaphthalenes (DMN) with maleonitrile (MN) and fumaronitrile (FN). From the measured KcDA, we found that MN complexes more strongly than FN with 1,4- and 1,5-DMN but that FN complexes more strongly with 2,3-DMN than does MN. These results are explained in terms of more than one favourable geometry for the ct complexes, since the donors are relatively large compared to the acceptors.Irradiation of the ct complexes between 1,4-, 1,5-, or 2,3-DMN and 1,2-dicyanoethylene led to isomerization of the olefins. The photostationary state depends on the absorption spectra of the ct complexes formed between the donor and the isomeric olefins. From spectroscopic and photo-CIDNP studies, we find evidence that the isomerization in polar solvents takes place via the triplet state of the olefin. The triplet is formed from the radical ion pair resulting after excitation of the ct complex.

Measurement of the Rate of Reaction of Potassium Iodide with Organic Chlorides in Dilute Acetone Solution

1944 ◽  
Vol 66 (11) ◽  
pp. 1987-1988 ◽  
Author(s):  
Kenneth L. Senior ◽  
Richard R. Hetrick ◽  
John G. Miller
Keyword(s):  
Potassium Iodide ◽  
Acetone Solution ◽  
Rate Of Reaction
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