Search by property

This page provides a simple browsing interface for finding entities described by a property and a named value. Other available search interfaces include the page property search, and the ask query builder.

List of results

( # Submitochondrial particles have been sequentially treated with trypsin )

Singer 1956 J Biol Chem + ( # Succinic dehydrogenase has been iso … # Succinic dehydrogenase has been isolated from beef heart mitochondria as a soluble protein in a state approaching homogeneity by physico-chemical criteria. The overall purification is about 100-fold compared with a mitochondrial acetone powder. # The enzyme is a ferroflavoprotein cont,aining 4 atoms of ferrous (non-hemin) iron and a mole of flavin per mole of protein (200,000 gm.). The dehydrogenase may be isolated from aged starting material with 2 atoms of iron per mole and half the specific activity. # Among the common electron acceptors, only the following function with the dehydrogenase, at the relative rates indicated in parentheses: phenazine methosulfate (100), ferricyanide (39), O2 (0.02). The first two of these acceptors react via the iron moieties, whereas O2 seems to react directly with the flavin. # The QO2, has been measured as 20,000 and the turnover number as 3000 under the standard assay conditions. # The properties of the isolated dehydrogenase agree with those previously described for mitochondrial and other particulate preparations of the enzyme, except for properties related to the absence of contaminating hemoproteins. At 38 °C the pH optimum is 7.7; the K, for succinate is 1.3 X 10-3 M at 38 °C and 5.2 X 10-4 M at 21 °C. Oxalacetate, malonate, and fumarate are competitive inhibitors. Antimycin A and BAL do not inhibit the dehydrogenase. The dehydrogenase is highly sensitive to sulfhydryl reagents, p-chloromercuribenzoate inhibiting it in a reversible manner and the substrate protecting the enzyme from this type of inhibition. enzyme from this type of inhibition. )
Chance 1961 J Biol Chem-IV + ( # The pathway of electron transfer f … # The pathway of electron transfer from succinate to pyridine nucleotide shows a sensitivity to antimycin A, suggesting that carriers of the respiratory chain up to and including the antimycin-sensitive point are involved in succinate-linked reduction of pyridine nucleotide.# The sensitivity of succinate-linked reduction of pyridine nucleotide to Amytal suggests that a reverse of the flavoprotein-pyridine nucleotide interaction observed in the oxidation of pyridine nucleotide in phosphorylating mitochondria is also part of the electron transfer pathway. # Mechanisms indicating the interconnection of electrons from the antimycin-sensitive point to this flavoprotein via electron carriers such as cytochrome b and ubiquinone are considered. These mechanisms appear to apply to both aerobic and anaerobic (terminally inhibited) energy-linked reduction of pyridine nucleotide. # Three mechanisms for increased reduction of pyridine nucleotide in succinate-treated mitochondria that do not involve the above pathway fail to show responses of the experimentally observed sensitivity to Amytal or to antimycin A. # The properties of the energy-linked pool of pyridine nucleotide in metabolism are considered. Its participation is likely to be small in state 3 and of some consequence in state 4. and of some consequence in state 4. )
Pullman 1960 J Biol Chem + ( # The purification o f a soluble ATP … # The purification o f a soluble ATPase from beef heart mitochondria is described. The activity is dependent on Mg++ and is stimulated by 2,4-dinitrophenol. The enzyme cleaves the terminal phosphate of ATP and is inhibited by ADP. The activity is therefore assayed in the presence of an ATP regenerating system. # The enzyme is cold labile. Although stable at room temperature, the enzyme rapidly loses activity at 4°. ATP, which protects the enzyme against inactivation by heat and dialysis, does not prevent the cold inactivation. # Attempts to demonstrate an exchange between either Pi32 or C14-ADP and ATP in the presence of the enzyme were unsuccessful. # The properties of the purified enzyme are discussed in relation to particulate mitochondrial ATPase and to myosin ATPase.ochondrial ATPase and to myosin ATPase. )
Ragan 1973 J Biol Chem + ( # The ability to phosphorylate ADP during … # The ability to phosphorylate ADP during oxidation of NADH by ubiquinone-1 was restored to the NADH-ubiquinone reductase complex by combining the latter with phospholipids and a hydrophobic protein fraction derived from bovine heart mitochondria.# Phosphorylation was abolished by rotenone, uncoupling agents, or rutamycin. The efficiency of ATP formation was as high as 0.5 mole per mole of NADH oxidized under optimal conditions.# Reconstitution of phosphorylation had an absolute requirement for phosphatidylethanolamine and a partial requirement for phosphatidylcholine, a molar ratio of approximately 4:1 being optimal. A much more marked requirement for phosphatidylcholine was observed in the presence of low concentrations of cardiolipin (0.05 to 1.5% of the total phospholipid). In the presence of cardiolipin, an equal molar ratio of phosphatidylethanolamine to phosphatidylcholine gave the highest phosphorylation efficiency.# The NADH-ubiquinone reductase complex is oriented in the reconstituted vesicles such that approximately 50% of the molecules can react with added NADH. Reaction of all the molecules with NADH occurs in the presence of 0.5% deoxycholate.# Phosphorylation efficiency can be significantly improved by purification of the vesicles on sucrose density gradients. the vesicles on sucrose density gradients. )
Loew 1963 Biochim Biophys Acta + ( # The reduction of added DPN by succinate … # The reduction of added DPN by succinate catalyzed by submitochondrial particles from beef heart has been studied.# The reduction was endergonic and required specifically the addition of ATP.# The reaction had a limited specificity for electron acceptors; six DPN analogues tested were reduced at the same rate or nearly the same rate, as was DPN. TPN was only reduced at a very slow rate.# The rate of reduction was influenced by phosphate and ADP and their effects became pronounced if added together.# The effect of DPNH was marked only if added in a concentration equal to or exceeding that of DPN.# Respiratory inhibitors acting in the flavin region of the respiratory chain blocked the reaction.the respiratory chain blocked the reaction. )
Slater 1953 Biochem J + ( # The α-ketoglutaric oxidase system of he … # The α-ketoglutaric oxidase system of heartmuscle sarcosomes has a pH optimum at 7.4. The yield of oxidative phosphorylation (P:O ratio) is unchanged between pH 6.2 and 7.7.# Hypertonic sucrose (0.88 M) is an inhibitor of the succinic oxidase system in the Keilin & Hartree preparation. Its major effect appears to be on the accessibility of both the endogenous and added cytochrome ''c'' to the other components of the system.# Maximum activity of the α-ketoglutaric oxidase system of heart-muscle sarcosomes is obtained under the most highly hypotonic conditions studied, equivalent to about one-third isotonic. Under these conditions, sarcosomes are swollen, but shrink again when placed in isotonic medium. The effect of tonicity on the activity of the α-ketoglutaric oxidase system is also reversible. # As the tonicity is increased by saline, sucrose or phosphate, the activity of the α-ketoglutaric oxidase system decreases.# The P:O ratio is not affected over a wide range of sucrose concentrations which have a marked effect on the activity of the α-ketoglutaric oxidase system. This and other examples where the oxidase system is more sensitive than the P:O ratio to variations of the conditions indicates that the phosphorylative enzymes are normally in excess of the purely oxidative enzymes and increases the likelihood that measurements of the yield of oxidative phosphorylation on isolated tissue preparations represent the state of affairs in the cell. # Phosphate, in high concentration, decreases the P:O ratio; the optimal concentration is 0.03 M. # Hypertonic sucrose is unsuitable for the isolation of sarcosomes. There is, however, no significant difference between sarcosomes isolated with isotonic sucrose and isotonic saline, except that the latter are deficient in cytochrome ''c''.t the latter are deficient in cytochrome ''c''. )
Gear 1970 Biochem J + ( # [[Mitochondrial marker enzymes|Marker enzymes]] … # [[Mitochondrial marker enzymes|Marker enzymes]] for the mitochondrial matrix, inner membrane, inter-membrane space and outer membrane were measured in mitochondria isolated from control and regenerating rat liver. The specific activity of these enzymes was then followed for up to 30 days after operation. # The specific activity of marker enzymes for the matrix, inner membrane and inter-membrane space remained constant during liver regeneration.# However, the specific activities of monoamine oxidase and kynurenine hydroxylase, both outer-membrane markers, fell by 67% and 49% respectively from their control values at 4 days after operation, and returned to normal by about 3 weeks.# The repression of kynurenine hydroxylase activity was shown to be unrelated to any independent variation in tryptophan catabolism, based on tryptophan pyrrolase assays.# These results are considered to indicate that enzymes of the inner and outer mitochondrial membranes are synthesized asynchronously during morphogenesis.# The enzyme complement of purified outer membrane at 4 days after operation was about 50% of that of the appropriate control. Thus the composition of the outer membrane itself may vary dramatically, and supports the concept that constitutive enzymes may turn over independently of a membrane's existence.# The behaviour of the rotenone-insensitive, NADH cytochrome c reductase did not parallel the other outer-membrane enzymes for intact mitochondria, but did so when assayed in highly purified fractions of outer membrane. This suggests a labile binding to the outer membrane during the early stages of morphogenesis.# Electrophoresis of inner- and outer-membrane proteins revealed little difference between control and experimental mitochondria at 4 days, except for an increase in several, high-molecular-weight components of the outer membrane. These bands closely correspond to similar bands derived from smooth endoplasmic reticulum.# The results are discussed in relation to the biogenesis and turnover of mitochondria, and are considered to provide evidence for turnover as a unit, at least for the matrix, inner membrane, inter-membrane space and possibly some form of primary outer membrane.ssibly some form of primary outer membrane. )
Burtscher 2022 Antioxid Redox Signal + ('''''Significance:''''' Oxygen is indispen … '''''Significance:''''' Oxygen is indispensable for aerobic life, but its utilization exposes cells and tissues to oxidative stress; thus, tight regulation of cellular, tissue, and systemic oxygen concentrations is crucial. Here, we review the current understanding of how the human organism (mal-)adapts to low (hypoxia) and high (hyperoxia) oxygen levels and how these adaptations may be harnessed as therapeutic or performance enhancing strategies at the systemic level. '''''Recent Advances:''''' Hyperbaric oxygen therapy is already a cornerstone of modern medicine, and the application of mild hypoxia, that is, hypoxia conditioning (HC), to strengthen the resilience of organs or the whole body to severe hypoxic insults is an important preparation for high-altitude sojourns or to protect the cardiovascular system from hypoxic/ischemic damage. Many other applications of adaptations to hypo- and/or hyperoxia are only just emerging. HC-sometimes in combination with hyperoxic interventions-is gaining traction for the treatment of chronic diseases, including numerous neurological disorders, and for performance enhancement. '''''Critical Issues:''''' The dose- and intensity-dependent effects of varying oxygen concentrations render hypoxia- and/or hyperoxia-based interventions potentially highly beneficial, yet hazardous, although the risks versus benefits are as yet ill-defined. '''''Future Directions:''''' The field of low and high oxygen conditioning is expanding rapidly, and novel applications are increasingly recognized, for example, the modulation of aging processes, mood disorders, or metabolic diseases. To advance hypoxia/hyperoxia conditioning to clinical applications, more research on the effects of the intensity, duration, and frequency of altered oxygen concentrations, as well as on individual vulnerabilities to such interventions, is paramount.ities to such interventions, is paramount.)
MiP2017/MitoEAGLE Hradec Kralove CZ + ('''12th Conference … '''12th Conference on Mitochondrial Physiology and MitoEAGLE WG and MC Meeting, 2017, Hradec Kralove, Czech Republic.'''Co-organized with COST Action MitoEAGLE: [[COST_Action_MitoEAGLE#Grant_periods |Management Committee Meeting and Working Group Meetings]].[[COST_Action_MitoEAGLE#Grant_periods |Management Committee Meeting and Working Group Meetings]].)
MiP2018/MitoEAGLE Jurmala LV + ('''13th Conference on Mitochondrial Physiology and MitoEAGLE WG and MC Meeting, 2018, Jurmala, Latvia.''')
IOC13 + ('''13th Workshop on High-Resolution Respirometry.''' Innsbruck, Tyrol, Austria; 1997 May 09-16. :>> O2k-Workshop: [[Oroboros Events| Current dates]] :>> Product: [[Oroboros O2k]], [[Oroboros O2k-Catalogue | O2k-Catalogue]])
ASMRM 2017 Xian CN + ('''14thConference of the Asian Society of Mitochondrial Research and Medicine'''. Xi'an, Shaanxi, China; 2017 September.)