Membrane mitochondria

Mitochondria membrane-enclosed subcehular organelles that possess a small genome and are principally concerned with energy generation. 

Particles that are smaller and less dense than the nuclei can be obtained by step-by-step acceleration of the gravity on the supernatant left over from the first centrifugation. However, this requires very powerful centrifuges (high-speed centrifuges and ultracentrifuges). The sequence in which the fractions are obtained is mitochondria, membrane vesicles, and ribosomes. Finally, the supernatant from the last centrifugation contains the cytosol with the cell s soluble components, in addition to the buffer. 

Introduction of HM mixture induced passive permeability of mitochondria membranes for K, and resulted in aggravation of proton permeability (Fig. 22.3). Statistically significant differences in swelling rate of mitochondria isolated from the rat liver between different animal groups, was observed in ammonium nitrate medium from the second minute tiU the end of the experiment. Similar dynamics... 

Lipids are mostly more or less long hydrocarbon chain molecules, constituting particularly the cell membranes and the mitochondria membrane (Figs. 3.51 and 3.52). 

Studies with various subcellular fractions are useful to ascertain which enzyme systems are involved in the metabolism of a chug candidate. In the absence of added cofactors, oxidative reactions such as oxidative deamination that are supported by mitochondria or by Ever microsomes contaminated with mitochondria membranes (as is the case with microsomes prepared from frozen liver samples) are likely catalyzed by monoamine oxidase (MAO), whereas oxidative reactions supported by cytosol are likely catalyzed by aldehyde oxidase and/or xanthine oxidase (a possible role for these enzymes in the metabolism of... 

Figure 1 A schematic representation of the Ca + transporters of animal cells. Plasma membrane (PM) channels are gated by potential, ligands or by the emptying of Ca + stores. Channels in the ER/SR are opened by lnsP3 or cADPr (the cADPr channel is sensitive to ryanodine and is thus called RyR). ATPase pumps are found in the PM (PMCA), in the ER/SR (SERCA), and in the Golgi apparatus (SPCA). The nuclear envelope, which is an extension of ER, contains the same transporters of the latter. NCXs are located in the PM (NCX) and in the inner mitochondria membrane (mNCX). A uniporter (U) driven by the internal negative potential (-180 mV) transports Ca + into mitochondria. Ca +-binding proteins are represented with a sphere containing the four EF-hands Ca +.binding sites.

Calculate the ApH across the inner mitochondria membrane that is required at 25 C to drive the synthesis of ATP from ADP + P under standard conditions. 

Mitochondria damage Mitochondria membrane potential dyes (e.g., TMRM) [52]... 

Pyranine has three sulfono groups and is a very water soluble dye. When dry phospholipids are swelled in dilute solutions of pyranine (2 mM or less), multilamellar vesicles are formed where the dye is entrapped, almost exclusively, in the outer aqueous layers. A suspension of such vesicles in water provides a model for the water layers that exist in the folding of mitochondria membranes or the packed lamellae of thylakoids. 

The 3 1 mixture of 226 and 227 completely inhibited the incorporation of the appropriate radioactive precursors into DNA, RNA and proteins in Jurkat cells at a concentration of 1.9 pM. This is suggested to be a consequence of the breakdown of the mitochondrias membrane potential. 

Reacts with thiol groups in mitochondria Membrane potential dependent accumulation Endocytosed into acidic compartments Weak base is protonated and accumulated Actin Tubulin... 

The second phase, proposed by Moghimi et al., was said to occur 24 h after exposure, and consisted of a loss of mitochondrial membrane potential which was revealed by translocation of phosphatidylserine as a consequence of PEI-induced channel formation. This led to release of the pro-apoptotic cytochrome c and subsequent activation of caspases-3 triggering apoptosis. Mitochondrial-mediated apoptotic events induced by polycations have also been reported in cell lines treated with high MW PLL in free form, DNA polyplexes and PAMAM dendrimers. In the study by Lee et al., PAMAM dendrimers around 45 nm in size exhibited mitochondrial co-localization, decreased expression of mitochondrial genes and mitochondria membrane... 

The membranes surrounding each cell (plasma membrane) and the intracellular structures (endoplasmatic reticulum, Golgi apparatus, nuclear membrane, mitochondria membranes, other organelle membrane) are not only composed of lipids but incorporate proteins and steroids as well. Besides this, adsorbed proteins will greatly influence the functionality of the membrane. Integral proteins can span the entire membrane. A considerable fraction of these proteins facilitates transmembrane transport of species usually not permeating the membrane. The transport mechanism may be very different. One group involves carriers... 

Several oxPC species, such as PGPC, PONPC, and PAzPC, were shown to induce mitochondria dysfunction and promote apopotic cell death. Endogenonsly produced or internalized via the TMEM30a transporter, truncated oxPC can directly intercalate into the mitochondria manbrane and thus induce mitochondria membrane depolarization, swelling, and mitochondria permeability transition (MPT) pore... 

Following the eatalytic reaction to form long-chain fatty acyl-CoA, the enzymatic reaction of carnitine palmitoyltranferase I (CPT-1) replaces CoA with carnitine to form fatty acylcamitine [62]. This conversion allows fatty acids to be transported from the cytoplasm to the inner mitochondrial membrane via carnitine acylcamitine translocase. Once across the inner mitochondria membrane, fatty acylcamitine is reversely converted back to long-chain fatty acyl-CoA by carnitine palmitoyltrandferase II (CPT-2) for subsequent P-oxidation [63, 64]. Each p-oxidation cycle removes a two carbon unit and involves four main enzymes 1) aeyl-CoA dehydrogenase, 2) enoyl-CoA hydratase, 3) 3-hydroxyacyl-CoA dehydrogenase, and 4) P-ketothiolase [65]. The net reaction of each P-oxidation pathway is ... 

Feedback mode SECM imaging was successfully employed to map metabolic activities with high spatial resolution. Heterogeneous distributions of active NADH cytochrome reductase within individual mitochondria membrane surfaces were visualized [43]. However, as suggested by Bard s group, this mode will not generally be accessible for surfaces with relatively lower enzymatic activities. On the other hand, the G/C mode may offer wider applicability for imaging biocatalytic reactions... 

We have studied the electrophysiological properties of outer mitochondria membranes incorporated in liposomes, using the patch-clamp technique. The proteoliposomes were prepared and enlarged in 150 mM KCl, 0.1 mM CaCh, and 20 mM HEPES, and the same solution was used in the recording pipette. Liposome-attached and inside-out patches were obtained. 

Considerable work has been directed to the search for better neutral carriers, motivated by the very successful valinomycin sensor for potassium (23-2II). Impetus was given to the development of this electrode by the observation of Moore and Pressman (102) that the antibiotic is capable of actively transporting potassium across rat mitochondria membranes. There are numerous synthetic macrocyclic polyethers capable of forming complexes with monovalent cations. Some of the earliest ISE studies were by Rechnitz and Eyal (103) on dicyclohexyl- and dibenzo-l8-crown-6 ligands synthesized by Pedersen (104). Soon... 

In particular, they make the architecture of the cell and the mitochondria membranes (Fig. 3.60). 

This combination of activities of Plnronic in MDR cells is due to the amphiphilic surfactant architecture of the block copolymer molecules, which can incorporate into cellular membranes resulting in changes in membrane permeability, membrane potential, and membrane transport of various compounds. The likely targets of Plmonic effects are the cell plasma membrane (where Pgp is localized) and the mitochondria membrane, where Plnronic affects normal functioning of the drug efflux transporters and respiratory chain, respectively [28,32]. Selected Pluronics, which can translocate inside the cell and thus affect intracellular compartments, in particular mitochondria, are the most efficacious modulators in both Pgp inhibition and ATP depletion [28]. 

The redox species involved in the electron transfer steps are part of the electron transport chain (Figure 9.25) located in the inner mitochondria membrane. They are proteins that pass electrons from one protein to another, and each time some of the energy is used to move protons through the cell membrane. The reaction that ultimately drives the electron transport chain is the oxidation of hydrogen molecules to form water molecules ... 

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