Control of adenine nucleotide metabolism in hepatic mitochondria from rats with ethanol-induced fatty liver

Male rats developed fatty liver after being fed on an ethanol-containing diet for 31 days. Liver mitochondria from these animals catalysed ATP synthesis at a slower rate when compared with mitochondria from pair-fed control rats (control mitochondria), and demonstrated lowered respiratory control with succinate as substrate, owing to a decrease in the State-3 respiratory rate. Respiration in the presence of uncoupler was comparable in mitochondria from both groups of rats. Translocation of both ATP and ADP was decreased in mitochondria from ethanol-fed rats, with ADP uptake being lowered more dramatically by ethanol feeding. Parameters influencing adenine nucleotide translocation were investigated in mitochondria from ethanol-fed rats. Experiments performed suggested that lowered adenine nucleotide translocation in these mitochondria is not the result of inhibition of the translocase by either long-chain acyl-CoA derivatives or unesterified fatty acids. Analysis of endogenous adenine nucleotides in these mitochondria revealed lowered ATP concentrations, but no decrease in total adenine nucleotides. In experiments where the endogenous ATP in these mitochondria was shifted to higher concentrations by incubation with oxidizable substrates or defatted bovine serum albumin, the rate of ADP translocation was increased, with a linear correlation being observed between endogenous ATP concentrations and the rate of ADP translocation. The depressed ATP concentration in mitochondria from ethanol-fed rats suggests that the ATP synthetase complex is replenishing endogenous ATP at a slower rate. The lowered ATPase activity of the ATP synthetase observed in submitochondrial particles from ethanol-fed animals suggests a decrease in the function of the synthetase complex. A decrease in the rate of ATP synthesis in mitochondria from ethanol-fed rats is sufficient to explain the decreased ADP translocation and State-3 respiration.     

Effects of Sclerin on Energy-linked Functions and Phospholipase Activity in Mitochondria Isolated from Rat Liver and Some Plants

Sclerin (SCL) not only elevated the respiratory control ratio and ADP/O ratio in mitochondria isolated from rat liver and some plants, but was effective in maintaining the energy-linked functions in these mitochondria during aging. There was a close relationship in the effect of SCL between the liberation of fatty acid and maintenance of the energy-linked functions in mitochondria during aging. The liberation of fatty acid was mainly due to the digestion of mitochondrial phospholipids by endogenous phospholipase. SCL had no effect on the activity of phospholipase and rather raised the level of endogenous phospholipase in mitochondria during aging at 30°C. The activity of phospholipase in mitochondria was inhibited by ATP, but stimulated by DNP. It was supposed that SCL inhibits the activity of phospholipase through ATP or high-energy intermediates which is maintained in mitochondria during aging. SCL had a protective effect on the activity of DNP-activated ATPase in mitochondria stored in the cold, and, at a very low concentration, stimulated the ATP-driven NAD reduction by mitochondria.     

Phospholipid Dependence of the Reversible,Energy-Linked,Mitochondrial Transhydrogenase in <Emphasis Type="Italic">Manduca sexta</Emphasis>

Midgut mitochondria from fifth larval instar Manduca sexta exhibit a membrane-associated transhydrogenase that catalyzes hydride ion transfer between NADP(H) and NAD(H). The NADPH-forming transhydrogenations occur as nonenergy- and energy-linked activities. The energy-linked activities couple with electron transport-dependent utilization of NADH/succinate, or with Mg²⁺-dependent ATPase. These energy-linked transhydrogenations have been shown to be physiologically and developmentally significant with respect to insect larval/pupal maturation. In the present study, isolated mitochondrial membranes were lyophilized and subjected to organic solvent or phospholipase treatments. Acetone extraction and addition of Phospholipase A₂ proved to be effective inhibitors of the insect transhydrogenase. Liberation of phospholipids was reflected by measured phosphorous release. Addition of phospholipids to organic solvent- and phospholipase-treated membranes was without effect. Employing a partially lipid-depleted preparation, phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine were reintroduced and transhydrogenase activity assessed. Of the phospholipids tested, only phosphatidylcholine significantly stimulated transhydrogenase activity. The results of this study suggest a phospholipid dependence of the M. sexta mitochondrial transhydrogenase.     

Mitochondrial phospholipase A2 activity and mitochondrial aging

The changes in mitochondrial phospholipid metabolism and energy-linked functions have been followed as coupled mitochondria are allowed to age in isotonic sucrose at 18 degrees C. Analysis of the aging process has provided an approach for studying the structure--function relationships within the mitochondrion without adding external agents to perturb the membrane structure. The initial event observed in this process of deterioration is a loss of respiratory control which is paralleled by diminishing levels of ATP. As ATP levels decline, so do the rates of reacylation of monoacyglycerophosphorylethanolamine and fatty acid oxidation. In most cases the previously inactive phospholipase A2 (EC 3.1.1.4, phosphatide-2-acyl-hydrolase) begins rapid hydrolysis of membrane phosphatidylethanolamine as ATP levels approach zero. The final energy-linked phenomenon observed to decline is the anilinonaphthalenesulfonic acid fluorescence response. Evidence is presented which suggests strongly that the activity of the mitochondrial phospholipase A2 on endogenous phospholipids is suppressed in tightly coupled mitochondria. This suppression is temporally linked to ATP levels in the mitochondria. Furthermore, this study demonstrates that mitochondria which are only slightly damaged have the potential to effect membrane repair through reacylation of monoacyl phospholipids.     

Control of state 3 respiration in liver mitochondria from rats subjected to chronic ethanol consumption

Male Sprague-Dawley rats were pair-fed a liquid diet containing 36% of calories as ethanol for at least 31 days. Mitochondria were isolated from the livers and assayed for state 3, state 4 and uncoupled respiration at all three coupling sites. Assay conditions were established that maximized state 3 respiration with each substrate while maintaining a high respiratory control ratio. In mitochondria from ethanol-fed animals, state 3 respiratory rates were decreased at all three coupling sites. The decreased state 3 rate observed at site III was still significantly higher than the state 3 rates observed at site II in mitochondria from either ethanol-fed or control animals. Moreover, the maximal (FCCP-uncoupled) rates with succinate and -ketoglutarate were the same in mitochondria from ethanol-fed and control animals, whereas with glutamate-malate as substrate it was lowered 23% by chronic ethanol consumption. To investigate the role of cytochrome oxidase in modulating the respiratory rate with site I and site II substrates, the effects of cyanide on state 3 and FCCP-uncoupled respiration were determined. When the mitochondria were uncoupled there was no decrease in the rate of succinate oxidation until the rates of ascorbate and succinate oxidation became equivalent. Conversely, parallel inhibition of ascorbate, succinate and glutamate-malate state 3 respiratory rates were observed at all concentrations (1–50 μM) of cyanide utilized. These observations suggest strongly that in coupled mitochondria ethanol-elicited decreases in cytochrome oxidase activity depress the state 3 respiratory rates with site I and II substrates.     

Ethanol-elicited alterations in the oligomycin sensitivity and structural stability of the mitochondrial F0 . F1 ATPase

Liver mitochondria from rats fed ethanol chronically demonstrated a 35% decrease in mitochondrial ATPase activity. Moreover, the ATPase activity was inhibited only 61% by addition of oligomycin. Treatment of mitochondria from ethanol-fed rats with the detergent, Lubrol-WX, caused the release of 36% of the F1 from the resulting inner membrane particles. In comparison, only 5% of the F1 was dissociated when control mitochondria were subjected to the Lubrol treatment. However, when the units of ATPase activity from the supernatant and particles obtained after Lubrol treatment were added together, their sums were equivalent in preparations from control and ethanol-fed animals. Moreover, polyacrylamide gel electrophoresis analyses indicated equal amounts of the alpha + beta subunits of F1 in mitochondria from control and ethanol-fed rats. Reconstitution experiments with urea particles and F1 prepared from both control and ethanol mitochondria revealed a decrease in oligomycin sensitivity which could be attributed to an alteration in the functioning of either the oligomycin sensitivity conferring protein or a membrane sector subunit that interacts with oligomycin. Analysis by reconstitution also demonstrated that there were no ethanol-elicited alterations in the properties of the F1 portion of the ATP synthase complex. These observations indicate that the activity of the ATP synthase complex is altered significantly by ethanol-elicited changes in the functioning of those polypeptides involved in modulating both oligomycin sensitivity and the association of F1 with membrane sector subunits.     

Control of state 3 respiration in liver mitochondria from rats subjected to chronic ethanol consumption

Male Sprague-Dawley rats were pair-fed a liquid diet containing 36% of calories as ethanol for at least 31 days. Mitochondria were isolated from the livers and assayed for state 3, state 4 and uncoupled respiration at all three coupling sites. Assay conditions were established that maximized state 3 respiration with each substrate while maintaining a high respiratory control ratio. In mitochondria from ethanol-fed animals, state 3 respiratory rates were decreased at all three coupling sites. The decreased state 3 rate observed at site III was still significantly higher than the state 3 rates observed at site II in mitochondria from either ethanol-fed or control animals. Moreover, the maximal (FCCP-uncoupled) rates with succinate and alpha-ketoglutarate were the same in mitochondria from ethanol-fed and control animals, whereas with glutamate-malate as substrate it was lowered 23% by chronic ethanol consumption. To investigate the role of cytochrome oxidase in modulating the respiratory rate with site I and site II substrates, the effects of cyanide on state 3 and FCCP-uncoupled respiration were determined. When the mitochondria were uncoupled there was no decrease in the rate of succinate oxidation until the rates of ascorbate and succinate oxidation became equivalent. Conversely, parallel inhibition of ascorbate, succinate and glutamate-malate state 3 respiratory rates were observed at all concentrations (1-50 microM) of cyanide utilized. These observations suggest strongly that in coupled mitochondria ethanol-elicited decreases in cytochrome oxidase activity depress the state 3 respiratory rates with site I and II substrates.     

Studies on rat liver mitochondria: 4. Enzyme activities in mitochondria preserved at 0-4 degrees C

Rat liver mitochondria, stored with the energy-linked functions preserved or in aging conditions, were used to assay the activity of various enzymes during five days. The preservation of energy-linked functions was monitored by the respiratory control coefficient. ATPase, cytochrome oxidase and NADH dehydrogenase showed increased activity when the energy-linked functions were preserved. In aging conditions, cytochrome oxidase, NADH dehydrogenase and ATPase showed decreased activity. The ATPase activity increased only when mitochondria were stored in the presence of inhibitors of the electron transport chain. The activity of NADH oxidase did not change, and succinate oxidase and succinate dehydrogenase showed a small decrease in their activity. The enzymes of the matrix, alpha-ketoglutarate dehydrogenase, malate dehydrogenase and aspartate aminotransferase showed little decrease in activity under either of the conditions of storage. The total protein content decreased slightly under both conditions of storage. These results show that the activity of the enzymes analysed was maintained at reasonable levels, when the energy-linked functions of isolated mitochondria were preserved.     

Effects of delipidation on proton translocation and ATPase activity in beef heart electron transport particles

Delipidation of beef heart electron transport particles with phospholipase A2 has been examined. When the particles were treated with the lipase and subjected to a low bovine serum albumin wash, ATPase activity was unaffected as was the lipid/protein ratio of the particles. However, energisation by ATP/Mg2+ was abolished. Furthermore, unsaturated but not saturated fatty acids discharged the steady-state ATP-driven membrane potential of control samples. When the phospholipase A2 hydrolysis products were removed, inhibition of energy-linked reactions in the lipid-depleted particles was still observed and was interpreted in terms of non-specific leaks in the vesicle membranes, and 'specific' leaks through impaired H+-ATPase complexes. ATPase activity was less susceptible to delipidation than energisation but was, nevertheless, strongly inhibited at 50 percent lipid depletion. Spin label studies indicated a decrease in the fluidity of particle membranes accompanying delipidation. Moreover, the discontinuity seen in Arrhenius plots of ATPase activity was shifted from 17 degrees C (control) to 22 degrees C at 50 percent phospholipid depletion. The data are consistent with a release of unsaturated fatty acids by phospholipase A2 rendering the transport particles both leakier and the membranes less fluid than controls.     

Midgut mitochondrial transhydrogenase in wandering stage larvae of the tobacco hornworm, Manduca sexta

Midgut mitochondria from fifth larval instar Manduca sexta exhibited a transhydrogenase that catalyzes the following reversible reaction: NADPH + NAD(+) <--> NADP(+) + NADH. The NADPH-forming transhydrogenation occurred as a nonenergy- and energy-linked activity. Energy for the latter was derived from the electron transport-dependent utilization of NADH or succinate, or from Mg++-dependent ATP hydrolysis by ATPase. The NADH-forming and all of the NADPH-forming reactions appeared optimal at pH 7.5, were stable to prolonged dialysis, and displayed thermal lability. N,N'-dicyclohexylcarbodiimide (DCCD) inhibited the NADPH --> NAD(+) and energy-linked NADH --> NADP(+) transhydrogenations, but not the nonenergy-linked NADH --> NADP(+) reaction. Oligomycin only inhibited the ATP-dependent energy-linked activity. The NADH-forming, nonenergy-linked NADPH-forming, and the energy-linked NADPH-forming activities were membrane-associated in M. sexta mitochondria. This is the first demonstration of the reversibility of the M. sexta mitochondrial transhydrogenase and, more importantly, the occurrence of nonenergy-linked and energy-linked NADH --> NADP(+) transhydrogenations. The potential relationship of the transhydrogenase to the mitochondrial, NADPH-utilizing ecdysone-20 monooxygenase of M. sexta is considered.     

Coconut oil induces short-term changes in lipid composition and enzyme activity of chick hepatic mitochondria

We studied the short-term effects of a 20% coconut oil supplementation to the chick diet on lipid composition of liver and hepatic mitochondria, and changes that occurred in mitochondrial-associated enzymes as a result of this diet. No significant differences were observed in the lipid contents of liver when young chicks were fed the experimental diet, whereas hepatic mitochondria rapidly changed in response to this diet. Total cholesterol significantly increased in mitochondria at 24 hours of coconut oil diet feeding and decreased when dietary treatment was prolonged for 5 to 14 days. Changes in total mitochondrial phospholipids showed an inverse profile. A significant decrease in phosphatidylethanolamine and an increase in sphingomyelin were found at 24 hours. The cholesterol/phospholipid molar ratio significantly and rapidly (24 hours) increased in mitochondria from treated animals. Cytochrome oxidase activity drastically increased after 24 hours of experimental diet feeding and lowered to the control values when dietary manipulation was prolonged for 5 to 14 days. ATPase activity showed an inverse profile. Changes in cytochrome oxidase activity were parallel to changes in the cholesterol/phospholipid molar ratio, whereas changes in ATPase activity showed an inverse correlation with changes in this molar ratio. To our knowledge, this is one of the first reports on the very rapid response (24 hours) of mitochondrial lipid composition and function to saturated fat feeding.     

Effect of catecholamine depletion on oxidative energy metabolism in rat liver, brain and heart mitochondria; use of reserpine

Regulation of mitochondrial functions in vivo by catecholamines was examined indirectly by depleting the catecholamines stores by reserpine treatments of the experimental animals. Reserpine treatment resulted in decreased respiratory activity in liver and brain mitochondria with the two NAD+-linked substrates: glutamate and pyruvate + malate with succinate ATP synthesis rate decreased in liver mitochondria only. With ascorbate + TMPD system, the ADP/O ratio and ADP phosphorylation rate decreased in brain mitochondria. For the heart mitochondria, state 3 respiration rates decreased for all substrates. In the liver mitochondria basal ATPase activity decreased by 51%, but in the presence of Mg2+ and/or DNP increased significantly. In the brain and heart mitochondria ATPase activities were unchanged. The energy of activation in high temperature range increased liver mitochondrial ATPase while in brain mitochondria reserpine treatment resulted in abolishment in phase transition. Total phospholipid (TPL) content of the brain mitochondria increased by 22%. For the heart mitochondria TPL content decreased by 19% and CHL content decreased by 34%. Tissue specific differential effects were observed for the mitochondrial phospholipid composition. Liver mitochondrial membranes were more fluidized in the reserpine-treated group. The epinephrine and norepinephrine contents in the adrenals decreased by 68 and 77% after reserpine treatment.     

Resistance to ethanol disordering of membranes from ethanol-fed rats is conferred by all phospholipid classes.

Phospholipids extracted from liver microsomes and mitochondria of ethanol-fed rats retained the resistance to membrane disordered by ethanol which is observed in the intact isolated membranes. The lipid extracts were separated into the major phospholipid classes (phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol from microsomes and phosphatidylcholine, phosphatidylethanolamine and cardiolipin from mitochondria) by preparative TLC. The extent of membrane disordering by ethanol of phospholipid vesicles composed of a mixture of phospholipids from ethanol-fed rats and controls was determined from the reduction of the order parameter of the spin-probe 12-doxyl-stearate. In contrast to previous reports, we found that all phospholipid classes from ethanol-fed rats confer resistance to disordering by ethanol. To a first approximation the extent of resistance was proportional to the fraction of lipids from ethanol-fed rats, regardless of the phospholipid head-group. Subtle differences between phospholipid classes may exist but were too small to measure accurately. Except for phosphatidylethanol, incorporation of anionic phospholipids did not have a significant effect on the sensitivity of phospholipid vesicles to the disordering effect of ethanol. Vesicles prepared from mixtures of various dioleoyl phospholipids and natural phospholipids did not indicate a clear effect of fatty acid saturation on the sensitivity to disordering by ethanol. Although the precise molecular changes that occur in phospholipids from ethanol-fed rats have not been fully characterized it appears that subtle changes in all phospholipid classes contribute to the resistance to ethanol disordering of these membranes.     

Translocation and binding of adenine nucleotides by rat liver mitochondria partially depleted of phospholipids.

1. Rat liver mitochondria were partially depleted of their phospholipids using phospholipase A prepared from porcine pancreas (substrate specificity, cardiolipin greater than phosphatidylethanolamine greater than phosphatidylcholine) or from Crotalus adamanteus venom (substrate specificity, phosphatidylethanolamine = phosphatidylcholine greater than cardiolipin). 2. Removal of only about 1% of the mitochondrial phospholipid with the pancreatic enzyme leads to 50% and 25% losses in ADP and ATP translocation, respectively. Concomitant with the loss in translocation is a decline in the ability of both carbonylcyanide m-chlorophenylhydrazone and Ca2+ to stimulate ATP translocation. 3. To achieve comparable losses in ADP and ATP translocation with the venom enzyme, it is necessary to remove about 8% of the total mitochondrial phospholipid. Following such treatment, carbonylcyanide m-chlorophenylhydrazone and Ca2+ are still capable of stimulating ATP translocation. 4. Control experiments involving treatment of the mitochondria with the products of phospholipase digestion indicate that the effects observed on the translocase reflect a loss of phospholipid from the membrane. 5. Binding studies indicate that the loss in adenine nucleotide translocation following phospholipase treatment cannot be accoundted for by an altered ability to bind adenine nucleotides to atractyloside-sensitive sites. 6. The data are interpreted in terms of a mechanism of adenine nucleotide translocation involving a lipoprotein carrier system, consisting of the translocator protein and phospholipids, possibly cardiolipin and phosphatidylethanolamine.     

Effects of Delipidation on Proton Translocation and ATPase Activity in Beef Heart Electron Transport Particles

Delipidation of beef heart electron transport particles with phospholipase A₂ has been examined. When the particles were treated with the lipase and subjected to a low bovine serum albumin wash, ATPase activity was unaffected as was the lipid/protein ratio of the particles. However, energisation by ATP/Mg²⁺ was abolished. Furthermore, unsaturated but not saturated fatty acids discharged the steady-state ATP-driven membrane potential of control samples. When the phospholipase A₂ hydrolysis products were removed, inhibition of energy-linked reactions in the lipid-depleted particles was still observed and was interpreted in terms of non-specific leaks in the vesicle membranes, and ‘specific’ leaks through impaired H⁺-ATPase complexes. ATPase activity was less susceptible to delipidation than energisation but was, nevertheless, strongly inhibited at 50 percent lipid depletion.

Spin label studies indicated a decrease in the fluidity of particle membranes accompanying delipidation. Moreover, the discontinuity seen in Arrhenius plots of ATPase activity was shifted from 17°C (control) to 22°C at 50 percent phospholipid depletion. The data are consistent with a release of unsaturated fatty acids by phospholipase A₂ rendering the transport particles both leakier and the membranes less fluid than controls.     

Effects of plant flavonoids on Manduca sexta (tobacco hornworm) fifth larval instar midgut and fat body mitochondrial transhydrogenase

The reversible, membrane-associated transhydrogenase that catalyzes hydride-ion transfer between NADP(H) and NAD(H) was evaluated and compared to the corresponding NADH oxidase and succinate dehydrogenase activities in midgut and fat body mitochondria from fifth larval instar Manduca sexta. The developmentally significant NADPH-forming transhydrogenation occurs as a nonenergy- or energy-linked activity with energy for the latter derived from either electron transport-dependent NADH or succinate utilization, or ATP hydrolysis by Mg++-dependent ATPase. In general, the plant flavonoids examined (chyrsin, juglone, morine, quercetin, and myricetin) affected all reactions in a dose-dependent fashion. Differences in the responses to the flavonoids were apparent, with the most notable being inhibition of midgut, but stimulation of fat body transhydrogenase by morin, and myricetin as also noted for NADH oxidase and succinate dehydrogenase. Although quercetin inhibited or stimulated transhydrogenase activity depending on the origin of mitochondria, it was without effect on either midgut or fat body NADH oxidase or succinate dehydrogenase. Observed sonication-dependent increases in flavonoid inhibition may well reflect an alteration in membrane configuration, resulting in increased exposure of the enzyme systems to the flavonoids. The effects of flavonoids on the transhydrogenation, NADH oxidase, and succinate dehydrogenase reactions suggest that compounds of this nature may prove valuable in the control of insect populations by affecting these mitochondrial enzyme components.     

Biochemical aspects of the mechanism of action of antiarrhythmic drugs on mitochondria. VII. Effect on energy-linked reactions and on membrane potential

Effects of the antiarrhythmic drugs (propranolol, perhexiline maleate, lidoflazine and iproveratril) on energy-linked reactions and on membrane potential were studied. Propranolol, perhexiline maleate and lidoflazine inhibit the ATPase activity of undamaged and broken mitochondria, and of submitochondrial particles. All drugs are inhibitors of either ATP-driven or of succinate-driven reduction of NADP+. The antiarrhythmics promote a decrease in the membrane potential upon energization of the mitochondrial membrane by alpha-ketoglutarate, succinate, or ATP. It was suggested that these drugs have a primary action on the mitochondrial membrane, thus altering the activities of membrane proteins (channels and enzymes).     

Effect of hyper- and hypothyroidism on phospholipid fatty acid composition and phospholipases activity in sarcolemma of rabbit cardiac muscle.

Lipid content and composition of fatty acids esterified to phospholipids of cardiac sarcolemma isolated from hyperthyroid, hypothyroid and control rabbits were analysed. Hyperthyroidism resulted in a significant reduction of the cholesterol to phospholipid molar ratio as compared to control animals, while hypothyroidism exerted the opposite effect. Complex changes in composition of phospholipid fatty acids observed in hyperthyroid state led to an elevation of the fatty acid unsaturation index over the control value. The unsaturation index value was, however, not affected in the hypothyroid state. Thyroxine hormone administration increased phospholipase A1 and decreased phospholipase A2 activity. The opposite effect was observed in thyreodectomized animals. The effect of changes in sarcolemmal bulk phospholipids upon thyroxine administration or deficiency on regulation of activity of membrane-bound enzymes is discussed.     

不同磷脂和糖脂对莱氏衣原体膜上Mg~（2＋）－ATPase活性的影响

莱氏衣原体膜上Ｍｇ~（２＋）－ＡＴＰａｓｅ用ＤＯＣ溶解后,经Ｓｅｐｈａｒｏｓｅ－６Ｂ和ＤＥＡＥ－ＣｅｌｌｕｌｏｓｅＤＥ－５２离子交换柱,得到了部分纯化的Ｍｇ~（２＋）ＡＴＰａｓｅ,并将此ＡＴＰａｓｅ与不同极性头部的磷脂和膜糖脂重组,研究了不同的极性头部的磷脂和膜糖脂对ＡＴＰａｓｅ活性的影响。此酶的活性不依赖酸性磷脂,ＰＧ、ＤＰＧ、大豆磷脂等明显抑制酶活性,中性磷脂ＤＭＰＣ、ＰＥ、ＰＣ则能增加酶活性,其中尤以非双层脂ＰＥ的作用最为明显。从莱氏衣原体膜上提取的糖脂（ＭＧＤＧ,ＤＧＤＧ）单独和ＡＴＰａｓｅ重组时,酶活性增加并不明显,当ＭＧＤＧ和ＤＧＤＧ以等比例混合时,能大大地增加酶活性。这表明Ｍｇ~（２＋）－ＡＴＰａｓｅ的活性很大程度上与磷脂的表面电荷及磷脂的组成相关。     

Thyroid hormones and phospholipase activity in rat liver mitochondria

The rate of the hydrolysis of mitochondrial phospholipids isolated from the liver of rats given excess amount of thyroid hormones for a long time was higher than in normal animals. Activation of this process determined by endogenous phospholipase of mitochondria could be also observed in liver mitochondria isolated 2 days after a single injection of L-thyroxine into rats. It is assumed that the hyperthyrosis-induced acceleration of lipid peroxidation in these organelles might be one of the reasons for activation of endogenous phospholipase of mitochondria.