Mechanism of activation of cytochrome C peroxidase activity by cardiolipin.
In this work, the actions of bovine heart cardiolipin, synthetic tetraoleyl cardiolipin, and a nonspecific anionic detergent sodium dodecyl sulfate (SDS) on cytochrome c (Cyt c) peroxidase activity recorded by chemiluminescence in the presence of luminol and on the Fe...S(Met80) bond whose presence was estimated by a weak absorption band amplitude with peak at 695-700 nm (A(695)) were compared. A strict concurrency between Fe...S(Met80) breaking (A(695)) and cytochrome peroxidase activity enhancement was shown to exist at cardiolipin/Cyt c and SDS/Cyt c molar ratios of 0 : 1 to 50 : 1 (by chemiluminescence). Nevertheless, when A(695) completely disappeared, Cyt c peroxidase activity under the action of cardiolipin was 20 times more than that under the action of SDS, and at low ligand/protein molar ratios (=4), SDS failed to activate peroxidase activity while cardiolipin enhanced Cyt c peroxidase activity 16-20-fold. A(695) did not change on Cyt c binding with liposomes consisting of tetraoleyl cardiolipin and phosphatidylcholine (1 : 10 : 10), while peroxidase activity was enhanced by a factor of 8. Breaking of 70% of the Fe...S(Met80) bonds resulted in only threefold enhancement of peroxidase activity. Cardiolipin-activated Cyt c peroxidase activity was reduced by high ionic strength solution (1 M KCl). The aggregated data suggest that cardiolipin activating action is caused, first, by a nonspecific effect of Fe...S(Met80) breaking as the result of conformational changes in the protein globule caused by the protein surface electrostatic recharging by an anionic amphiphilic molecule, and second, by a specific acceleration of the peroxidation reaction which is most likely due to enhanced heme accessibility for H(2)O(2) as a result of the hydrophobic interaction between cardiolipin and cytochrome.
Vladimirov
Yu A
YA
Faculty of Fundamental Medicine, Lomonosov Moscow State University, Moscow 117192, Russia. yuvlad@mail.ru
Proskurnina
E V
EV
Izmailov
D Yu
DY
Novikov
A A
AA
Brusnichkin
A V
AV
Osipov
A N
AN
Kagan
V E
VE
D000818:Animals; D002308:Cardiolipins / Q000494:pharmacology*; D002417:Cattle; D003578:Cytochrome-c Peroxidase / Q000378:metabolism*; D004789:Enzyme Activation; D006861:Hydrogen Peroxide / Q000378:metabolism; D007501:Iron / Q000737:chemistry; D008081:Liposomes / Q000378:metabolism; D008163:Luminescent Measurements; D008715:Methionine / Q000737:chemistry; D009994:Osmolar Concentration; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013053:Spectrophotometry
D002308:Cardiolipins; D008081:Liposomes; D012967:Sodium Dodecyl Sulfate; D008715:Methionine; D006861:Hydrogen Peroxide; D007501:Iron; D003578:Cytochrome-c Peroxidase