Ion permeability induction by the SH cross-linking reagents in rat liver mitochondria is inhibited by the free radical scavenger, butylhydroxytoluene

The relationship between the quantitative ratio of redox forms of ubiquinone and the degree of free radical damage to mitochondrial proteins in rat liver against the background of nutritional imbalance was investigated. The animals were divided into the following experimental groups: I – animals receiving full-value semi-synthetic ration (control group); II – animals receiving high-sucrose diet; III – animals receiving low-protein high-sucrose diet. The content of total and oxidized ubiquinone was determined spectrophotometrically at 275 nm, the content of reduced ubiquinone was determined by the difference between the content of total and oxidized ubiquinone. The intensity of the oxidative modification of proteins was assessed by the accumulation of carbonyl derivatives in the reaction with 2,4-dinitrophenylhydrazine (2,4-DNPH), the content of free SH-groups was assessed by using the Elman reagent. It was found that the most pronounced decrease in the content of total ubiquinone (almost twice) and the redistribution of its redox forms (reduction of the content of reduced ubiquinone by 7.2 times against the background of an increase in the level of oxidized ubiquinone by 2 times) in rat liver mitochondria is observed in animals that received a diet high in sucrose against the background of alimentary protein deprivation. In addition, the animals of this group showed the most pronounced free radical oxidation of mitochondrial proteins, as evidenced by a 3.5-fold increase in the content of carbonyl derivatives and a 2.6-fold decrease in the content of free protein SH- groups. It was shown that nutritional protein deficiency is a critical factor affecting the intensity of free radical processes in mitochondria. The established changes in the ratio of the redox forms of ubiquinone and the degree of oxidative modification of mitochondrial proteins in rat liver could be considered as prerequisites for deepening the energy imbalance and violation of the functional activity of mitochondria under conditions of nutritional imbalance.

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Demonstration of N- and C-terminal domain intramolecular interactions in rat liver carnitine palmitoyltransferase 1 that determine its degree of malonyl-CoA sensitivity

Biochemical Journal ◽

10.1042/bj20041533 ◽

2005 ◽

Vol 387 (1) ◽

pp. 67-76 ◽

Cited By ~ 27

Author(s):

Audrey FAYE ◽

Karen BORTHWICK ◽

Catherine ESNOUS ◽

Nigel T. PRICE ◽

Stéphanie GOBIN ◽

...

Keyword(s):

Rat Liver ◽

Liver Mitochondria ◽

Carnitine Palmitoyltransferase ◽

Intramolecular Interactions ◽

Rat Liver Mitochondria ◽

Cross Linking ◽

Terminal Domain ◽

Malonyl Coa ◽

Carnitine Palmitoyltransferase 1 ◽

Terminal Domains

We have previously proposed that changes in malonyl-CoA sensitivity of rat L-CPT1 (liver carnitine palmitoyltransferase 1) might occur through modulation of interactions between its cytosolic N- and C-terminal domains. By using a cross-linking strategy based on the trypsin-resistant folded state of L-CPT1, we have now shown the existence of such N–C (N- and C-terminal domain) intramolecular interactions both in wild-type L-CPT1 expressed in Saccharomyces cerevisiae and in the native L-CPT1 in fed rat liver mitochondria. These N–C intramolecular interactions were found to be either totally (48-h starvation) or partially abolished (streptozotocin-induced diabetes) in mitochondria isolated from animals in which the enzyme displays decreased malonyl-CoA sensitivity. Moreover, increasing the outer membrane fluidity of fed rat liver mitochondria with benzyl alcohol in vitro, which induced malonyl-CoA desensitization, attenuated the N–C interactions. This indicates that the changes in malonyl-CoA sens-itivity of L-CPT1 observed in mitochondria from starved and diabetic rats, previously shown to be associated with altered membrane composition in vivo, are partly due to the disruption of N–C interactions. Finally, we show that mutations in the regulatory regions of the N-terminal domain affect the ability of the N terminus to interact physically with the C-terminal domain, irrespective of whether they increased [S24A (Ser24→Ala)/Q30A] or abrogated (E3A) malonyl-CoA sensitivity. Moreover, we have identified the region immediately N-terminal to transmembrane domain 1 (residues 40–47) as being involved in the chemical N–C cross-linking. These observations provide the first demonstration by a physico-chemical method that L-CPT1 adopts different conformational states that differ in their degree of proximity between the cytosolic N-terminal and the C-terminal domains, and that this determines its degree of malonyl-CoA sensitivity depending on the physiological state.

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Hydroxy-Tyrosol as a Free Radical Scavenging Molecule in Polymeric Hydrogels Subjected to Gamma-Ray Irradiation

Processes ◽

10.3390/pr9030433 ◽

2021 ◽

Vol 9 (3) ◽

pp. 433

Author(s):

Mauro Fiorini ◽

Veronica Crognaletti ◽

Omar Sabry ◽

Lorenzo Scalise ◽

Paolo Fattori

Keyword(s):

Free Radical ◽

Gamma Ray ◽

Radical Scavenging ◽

Free Radical Scavenging ◽

Free Radical Scavenger ◽

Cross Linking ◽

Radical Scavenger ◽

Gamma Ray Irradiation ◽

Anti Oxidant ◽

Polymeric Hydrogels

Biomedical engineering is employing hydrogels with increasingly exciting possibilities for the treatment and regeneration of pathologically altered, degenerated, or traumatized tissues. Still, the sterilization processes may undesirably change the chemical and physical properties of hydrogels through cross-linking reactions. This work aims to characterize a new method of producing polyethylene oxide (PEO) hydrogels exploiting hydroxy-tyrosol (HT), an anti-oxidant molecule derived from olive leaf and olive oil, as a free radical scavenger to either prevent or limit gamma-ray-induced cross-linking. For this purpose, we produced hydrogels with PEO with two different buffer solutions (phosphate and citrate), varying HT concentration. We analyzed hydrogel preparations before and after gamma-ray irradiation, assessing the viscosity through rheological analysis and the chemical changes through IR analysis. We performed high-performance liquid chromatography (HPLC) analysis to measure residual HT in hydrogels after irradiation. The obtained results show that radiation-induced cross-linking and increase in viscosity of PEO hydrogels can be prevented by tailoring the concentration of HT as a free radical scavenging agent. Irradiation only consumes small amounts of HT; its presence in polymeric hydrogels can significantly impact biomedical applications by its anti-oxidant and anti-microbial activities.

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Free-radical metabolism of carbon tetrachloride in rat liver mitochondria. A study of the mechanism of activation

Biochemical Journal ◽

10.1042/bj2460313 ◽

1987 ◽

Vol 246 (2) ◽

pp. 313-317 ◽

Cited By ~ 60

Author(s):

A Tomasi ◽

E Albano ◽

S Banni ◽

B Botti ◽

F Corongiu ◽

...

Keyword(s):

Free Radical ◽

Carbon Tetrachloride ◽

Rat Liver ◽

Liver Microsomes ◽

Liver Mitochondria ◽

Rat Liver Mitochondria ◽

Radical Species ◽

Hypoxic Conditions ◽

Free Radical Species ◽

Transport Chain

Alterations in liver mitochondria as consequence of rat poisoning with carbon tetrachloride (CCl4) have been reported over many years, but the mechanisms responsible for causing such damage are still largely unknown. Isolated rat liver mitochondria incubated under hypoxic conditions with succinate and ADP were found able to activate CCl4 to a free-radical species identified as trichloromethyl free radical (CCl3) by e.s.r. spectroscopy coupled with the spin-trapping technique. The incubation of mitochondria in air decreased free-radical production, indicating that a reductive reaction was involved in the activation of CCl4. However, in contrast with liver microsomes (microsomal fractions), mitochondria did not require the presence of NADPH, and the process was not significantly influenced by inhibitors of cytochrome P-450. The addition of inhibitors of the respiratory chain such as antimycin A and KCN decreased free-radical formation by only 30%, whereas rotenone displayed a greater effect (approx. 84% inhibition), but only when preincubated for 15 min with mitochondria not supplemented with succinate. These findings suggest that the mitochondrial electron-transport chain is responsible for the activation of CCl4. A conjugated-diene band was observed in the lipids extracted from mitochondria incubated with CCl4 under anaerobic conditions, indicating that stimulation of lipid peroxidation was occurring as a result of the formation of free-radical species.

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Free radical scavenging action of the natural polyamine spermine in rat liver mitochondria

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2006.07.008 ◽

2006 ◽

Vol 41 (8) ◽

pp. 1272-1281 ◽

Cited By ~ 63

Author(s):

Irina G. Sava ◽

Valentina Battaglia ◽

Carlo A. Rossi ◽

Mauro Salvi ◽

Antonio Toninello

Keyword(s):

Free Radical ◽

Rat Liver ◽

Radical Scavenging ◽

Liver Mitochondria ◽

Free Radical Scavenging ◽

Rat Liver Mitochondria

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Cross-linking of minor subunits in the adenosine triphosphatase of rat liver mitochondria

Canadian Journal of Biochemistry ◽

10.1139/o77-167 ◽

1977 ◽

Vol 55 (10) ◽

pp. 1121-1124 ◽

Cited By ~ 5

Author(s):

P. D. Bragg ◽

C. Hou

Keyword(s):

Rat Liver ◽

Adenosine Triphosphatase ◽

Liver Mitochondria ◽

Rat Liver Mitochondria ◽

Cross Linking ◽

Disulfide Crosslinking ◽

Crosslinking Reagent

The subunits of the purified ATPase of rat liver mitochondria were cross-linked with the cleavable disulfide crosslinking reagent dithiobis(succinimidyl propionate). Besides cross-linking of the major (α,β) subunits interactions between β and γ and between γ and ε subunits were observed.

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