Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.3 (complex I)
 8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The smallest membrane-anchoring subunit (QPs3) of bovine heart succinate:ubiquinone reductase was overexpressed in Escherichia coli JM109 as a glutathione S-transferase fusion protein using the expression vector pGEX2T/QPs3. The yield of soluble active recombinant glutathione S-transferase-QPs3 fusion protein was isopropyl-1-thio-beta-D-galactopyranoside concentration-, induction growth time-, temperature-, and medium-dependent. Maximum yield of soluble recombinant fusion protein was obtained from cells harvested 3.5 h post-isopropyl-1-thio-beta-D-galactopyranoside (0.4 mM)-induction growth at 25 degrees C in 2.0% tryptone, 0.5% yeast extract, 10 mM NaCl, 2.5 mM KCl, 10 mM MgCl2, 20 mM glucose (SOC medium) containing 440 mM sorbitol and 2.5 mM betaine. QPs3 was released from the fusion protein by proteolytic cleavage with thrombin. Isolated recombinant QPs3 shows one protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis that corresponds to subunit V of mitochondrial succinate:ubiquinone reductase. Although purified recombinant QPs3 is dispersed in 0.01% dodecylmaltoside, it is in a highly aggregated form, with an apparent molecular mass of more than 1 million. The recombinant QPs3 binds ubiquinone, causing a spectral blue shift. Upon titration of the recombinant protein with ubiquinone, a saturation behavior is observed, suggesting that the binding is specific and that recombinant QPs3 may be in the functionally active state. Two amino acid residues, serine 33 and tyrosine 37, in the putative ubiquinone binding domain of QPs3 are involved in ubiquinone binding because the S33A- or Y37A-substituted recombinant QPs3s do not cause the spectral blue shift of ubiquinone. Although recombinant QPs3 contains little cytochrome b560 heme, the spectral characteristics of cytochrome b560 are reconstituted upon addition of hemin chloride. Reconstituted cytochrome b560 in recombinant QPs3 shows a EPR signal at g = 2.92. Histidine residues at positions 46 and 60 are responsible for heme ligation because the H46N- or H60N-substituted QPs3 fail to restore cytochrome b560 upon addition of hemin chloride.
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PMID:Identification of quinone-binding and heme-ligating residues of the smallest membrane-anchoring subunit (QPs3) of bovine heart mitochondrial succinate:ubiquinone reductase. 1008 11

Various stressful conditions such as ischemia in cold cardioplegic solutions and reperfusion occur during heart transplantation. Since ATP production is essential for the maintenance of contractile activity, mitochondrial function may be a mediator of ischemia and ischemia/reperfusion (I/R) injury. We aimed at testing the ability of two distinct cardioplegic solutions, Celsior (Cs) and Histidine Buffer (HBS), to protect rat heart mitochondria (HM) function during ischemia alone or ischemia followed by reperfusion. A standard Krebs-Henseleit solution (KH) was used as "negative" control. Male and Female Wistar rats were divided into control (Ctrl), reperfusion control (Ctrl_R), ischemia and I/R groups. Ischemia and I/R were divided into three subgroups depending on the cardioplegic solution used (Cs, HBS or KH) and subjected to 4-or 6-h ischemia alone or followed by reperfusion. HM respiration and transmembrane electric potential (Deltapsi) were measured with oxygen and TPP(+)-selective electrodes, respectively. Mitochondrial electron microscopy and detection of protein carbonyl groups content were also performed. After ischemic heart preservation, mitochondrial respiration and Deltapsi were not significantly affected except for the respiratory control ratio (RCR). After I/R, state 3 respiration, RCR and Deltapsi were decreased, especially in HM from male and for complex I substrates (CxI). HM preserved in HBS had less membrane disruption, segregation or disintegration. We conclude that (a) female HM were less sensitive to I/R, (b) CxI was particularly affected by I/R, (c) two cardioplegic solutions tested act in different mitochondrial targets preventing mitochondrial collapse.
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PMID:Mitochondrial preservation in Celsior versus histidine buffer solution during cardiac ischemia and reperfusion. 1975 1