The chemistry of pyrrolic compounds. XXVI. Porphyrins with negative groups in opposite pyrrolic ring systems

1974 ◽  
Vol 27 (2) ◽  
pp. 371 ◽  
Author(s):  
PS Clezy ◽  
CJR Fookes
Keyword(s):  
Cytochrome Oxidase ◽  
Diethyl Ester ◽  
Prosthetic Group ◽  
Ring Systems

The use of 4-acetyl(or ethoxycarbonyl)-5-formyl-2,2'-dipyrrylmethanes in the synthesis of porphyrins substituted with negative (electron-withdrawing) groups in opposite pyrrolic ring systems is discussed. A range of such porphyrins has been prepared including 2-formyl-6-vinyldeuteroporphyrin 11 diethyl ester, the synthesis of which duplicates the chromophoric system present in porphyrin-a, the prosthetic group of cytochrome oxidase.

Chemistry of pyrrolic compounds. XXX. An approach to the synthesis of porphyrin a

1975 ◽  
Vol 28 (12) ◽  
pp. 2703 ◽  
Author(s):  
PS Clezy ◽  
V Diakiw
Keyword(s):  
Cytochrome Oxidase ◽  
Dimethyl Ester ◽  
Oxidative Cyclization ◽  
Prosthetic Group ◽  
The North ◽  
East West

Synthesis of the porphyrin (1e) has been achieved by the oxidative cyclization of an appropriately substituted 1,19-dideoxy-1,19- dimethylbilene-b. It is hoped to use this tetrapyrrole to complete the synthesis of porphyrin a, the prosthetic group of cytochrome oxidase. New syntheses of Spirographis porphyrin and its isomer are reported. 2,4-Diacetyl- and 4-acetyl-2-methoxycarbonyl-deutero-porphyrin IX dimethyl ester have been prepared through bilene-b intermediates constructed in the ?east-west? rather than the ?north-south? mode.

scholarly journals The prosthetic group of cytochrome oxidase. 2. Chemistry of porphyrin a

1961 ◽  
Vol 78 (4) ◽  
pp. 798-806 ◽  
Author(s):  
P. S. Clezy ◽  
J. Barrett
Keyword(s):  
Cytochrome Oxidase ◽  
Prosthetic Group

The chemistry of pyrrolic compounds. XXXVIII. The synthesis of hexahydroporphyrin a and related compounds

1977 ◽  
Vol 30 (8) ◽  
pp. 1799 ◽  
Author(s):  
PS Clezy ◽  
CJR Fookes
Keyword(s):  
Cytochrome Oxidase ◽  
Side Chain ◽  
Prosthetic Group ◽  
Related Compounds

A procedure is described which allows the synthesis of porphyrins substituted with an α-hydroxy terpenoid side chain. Of particular significance is the preparation of the hexahydro derivative of porphyrin a, the iron-free prosthetic group of cytochrome oxidase.

Cytochrome c and cytochrome c oxidase interactions: the effects of ionic strength and hydrostatic pressure studied with site-specific modifications of cytochrome c

1992 ◽  
Vol 70 (7) ◽  
pp. 539-547 ◽  
Author(s):  
Jack A. Kornblatt ◽  
Janice Theodorakis ◽  
Gaston Hui Bon Hoa ◽  
Emmanuel Margoliash
Keyword(s):  
Hydrostatic Pressure ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Front Surface ◽  
Prosthetic Group ◽  
Binding Interaction ◽  
Cytochromes C ◽  
Heme Prosthetic Group ◽  
Full Charge

Seven cytochromes c, in which individual lysines have been modified to the propylthiobimane derivatives, have been prepared. These derivatives were also converted to the porphyrin cytochromes c by treatment with HF. The properties of both types of modified proteins were studied in their reactions with cytochrome c oxidase. The results show that lysines 25, 27, 60, 72, and 87 do not contribute a full charge to the binding interaction with the oxidase. These five residues, with the exception of the lysine-60 derivative, are on the front surface of the protein and contain the solvent-accessible edge of the heme prosthetic group. By contrast, lysines 8 and 13 at the top of the front surface do contribute a full charge to the binding interaction with the oxidase. The removal of the positive charge on any one lysine weakens the binding to cytochrome c oxidase by at least 1 kcal (1 cal = 4.1868 J). The presence of bimane at lysines 13 and 87 clearly forces the separation of the cytochrome c and oxidase, but this does not occur with the other complexes. The bimane-modified lysine-13 protein, and to a lesser extent that modified at lysine 8, show the interesting effect of enhanced complex formation with cytochrome c oxidase when subjected to pressure, possibly because of entrapment of water at the newly created interface of the complex. Our observations indicate that the two proteins of the cytochrome c – cytochrome oxidase complex have preferred, but not obligatory, spatial orientations and that interaction occurs without either protein losing significant portions of its hydration shell.Key words: cytochrome oxidase, cytochrome c, binding, hydrostatic pressure.

Comments on collision mechanics in ring systems

1984 ◽  
Vol 75 ◽  
pp. 407-422
Author(s):  
William K. Hartmann
Keyword(s):  
Asteroid Belt ◽  
Surface Erosion ◽  
Surface Layers ◽  
Ring Systems ◽  
Eclipse Observations ◽  
Saturn’S Rings ◽  
Saturn's Rings

ABSTRACTThe nature of collisions within ring systems is reviewed with emphasis on Saturn's rings. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Present-day collisions of such ring particles do not cause catastrophic fragmentation of the particles, although some minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Initial Polymerization Sites Indicated During Mitochondrial Oxidation of Diaminobenzidine after Toluene Treatment

1977 ◽  
Vol 35 ◽  
pp. 408-409
Author(s):  
W. A. Shannon ◽  
M. A. Matlib
Keyword(s):  
Membrane Permeability ◽  
Cytochrome Oxidase ◽  
Rat Liver ◽  
Precise Definition ◽  
Cytochemical Localization ◽  
Oxidative Reaction ◽  
Mitochondrial Oxidation ◽  
Definition Of ◽  
Exogenous Substrates

Numerous studies have dealt with the cytochemical localization of cytochrome oxidase via cytochrome c. More recent studies have dealt with indicating initial foci of this reaction by altering incubation pH (1) or postosmication procedure (2,3). The following study is an attempt to locate such foci by altering membrane permeability. It is thought that such alterations within the limits of maintaining morphological integrity of the membranes will ease the entry of exogenous substrates resulting in a much quicker oxidation and subsequently a more precise definition of the oxidative reaction.The diaminobenzidine (DAB) method of Seligman et al. (4) was used. Minced pieces of rat liver were incubated for 1 hr following toluene treatment (5,6). Experimental variations consisted of incubating fixed or unfixed tissues treated with toluene and unfixed tissues treated with toluene and subsequently fixed.

O activation in cytochrome oxidase and in other heme proteins

1992 ◽  
Vol 1101 (2) ◽  
pp. 192-194
Author(s):  
G BABCOCK ◽  
C VAROTSIS ◽  
Y ZHANG
Keyword(s):  
Cytochrome Oxidase ◽  
Heme Proteins
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