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Vasko N. Šarevski - One of the best experts on this subject based on the ideXlab platform.
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Water (R718) Centrifugal Compressors
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Influence of the refrigerant thermodynamic properties on the characteristics of centrifugal compressors is investigated. Peculiarities of centrifugal compressors working with various refrigerants are defined and the range of priority application is determined. Interdependence between centrifugal stage pressure ratio, peripheral Mach number and impeller peripheral speed, as well as the influence of the refrigeration capacity on the dimensions of centrifugal compressors are determined to obtain the range of reasonable usage of R718 refrigeration/heat pump systems. Deep vacuum operating conditions, low specific volumetric cooling capacity of R718, and Small Molecular Mass of water are the peculiarities that determine the main parameters of the water (R718) centrifugal compressors and the range of rational application of the R718 centrifugal refrigeration/heat pump systems. The high peripheral impeller speed, high Mach number, and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the compressor flow field.
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Water (R718) Turbo Compressor Refrigeration/Heat Pump Systems
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:R718 centrifugal refrigeration/heat pump systems are investigated to determine optimal schematic structure, to estimate performance characteristics, and to provide possibilities for wider application in the field of air-conditioning. Deep vacuum operating conditions, low specific volumetric cooling capacity, Small Molecular Mass, and high isentropic exponent of the water are peculiarities which determine the main parameters of centrifugal compressors and the range of rational application of R718 refrigeration/heat pump systems. High impeller peripheral speed, high Mach number, low Reynolds number, large dimensions, and high superheating at the compressor discharge are the features of R718 centrifugal refrigeration compressors. A two-stage centrifugal compressor and, respectively, two-stage refrigeration cycle are optimal technical solutions for refrigeration systems in the field of air-conditioning applications. Direct flash evaporation and condensation provide simplicity and the possibility of achieving a high COP. A comparison shows that R718 centrifugal refrigeration systems are competitive with traditional refrigeration systems.
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Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Abstract The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with Small Molecular Mass of the water and high isentropic exponent, result on high impeller peripheral speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons.
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Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with Small Molecular Mass of the water and high isentropic exponent, result on high impeller peripheral speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons. © 2013 Elsevier Ltd and IIR. All rights reserved.
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Characteristics of water vapor turbocompressors applied in refrigeration and heat pump systems
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Abstract Interdependence between centrifugal stage pressure ratio, peripheral Mach number and impeller peripheral speed, as well the influence of the refrigerating capacity on the dimensions of the centrifugal compressor are determined to obtain the range of reasonable usage of R718 refrigerating/heat pump systems. The deep vacuum operating conditions, the low specific volumetric cooling capacity of the R718 and the Small Molecular Mass of the water are the peculiarities which determined the main parameters of the centrifugal compressor and the range of rational application of the R718 refrigerating/heat pump systems. The high peripheral impeller speed, high Mach number and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the compressor flow field. Estimation of the flow characteristics and of the performance characteristics of the water vapor centrifugal compressors is presented, using results of CFD simulations and experimental investigations for high pressure ratio centrifugal compressors.
Jurgen Eckel - One of the best experts on this subject based on the ideXlab platform.
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Insulin-dependent translocation of the Small GTP-binding protein rab3C in cardiac muscle: studies on insulin-resistant Zucker rats
FEBS Letters, 1995Co-Authors: Ingo Uphues, Yijuang Chern, Jurgen EckelAbstract:Abstract The failure of insulin-regulated recruitment of the GLUT4 glucose transporter in cardiac muscle of obese Zucker rats is associated with alterations of the subcellular distribution of the Small-Molecular-Mass GTP-binding protein rab4A. Here, we show by subcellular fractionation and Western blotting a translocation of the Small-Molecular-Mass GTP-binding protein rab3C from microsomal membranes to plasma membranes in lean control rats following in vivo insulin stimulation. However, in cardiac muscle of obese animals no significant effect of the hormone on the subcellular distribution of rab3C was observed. In GLUT4-enriched membrane vesicles, obtained from cardiac microsomes of the obese group as well as of lean controls, rab3C was not detectable. It is suggested that the altered behaviour of rab3C may contribute to an impaired trafficking of GLUT4 in the insulin-resistant state.
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failure of insulin regulated recruitment of the glucose transporter glut4 in cardiac muscle of obese zucker rats is associated with alterations of Small Molecular Mass gtp binding proteins
Biochemical Journal, 1995Co-Authors: Ingo Uphues, T Kolter, B Goud, Jurgen EckelAbstract:Cardiac ventricular tissue of lean and genetically obese (fa/fa) Zucker rats was used to study the expression, subcellular distribution and insulin-induced recruitment of the glucose transporter GLUT4 and to elucidate possible Molecular alterations of the translocation process. Hearts were removed from basal and insulin-treated (20 min) lean and obese Zucker rats, and processed for subcellular fractionation and Western blotting of proteins. In obese rats, the total GLUT4 content in a crude membrane fraction was reduced to 75 +/- 8% (P = 0.019) of lean controls. In contrast, GLUT4 abundance in plasma membranes was not significantly different between lean and obese rats with a concomitant decrease (47 +/- 3%) in the microsomal fraction of obese animals. In plasma membranes of lean animals insulin was found to increase the GLUT4 abundance to 294 +/- 43% of control with a significantly (P = 0.009) reduced effect in the obese group (139 +/- 10% of control). In these animals insulin failed to recruit GLUT4 from the microsomal fraction, whereas the hormone induced a significant decrease (41 +/- 4%) of microsomal GLUT4 in lean controls. In GLUT4-enriched membrane vesicles, obtained from cardiac microsomes of lean rats, a 24 kDa GTP-binding protein could be detected, whereas no significant labelling of this species was observed in GLUT4 vesicles prepared from obese animals. In addition to the translocation of GLUT4, insulin was found to promote the movement of the Small GTP-binding protein rab4A from the cytosol (decrease to 61 +/- 13% of control) to the plasma membrane (increase to 177 +/- 19% of control) in lean rats with no effect of the hormone on rab4A redistribution in the obese group. In conclusion, cardiac glucose uptake of insulin-resistant obese Zucker rats is subject to multiple cellular abnormalities involving a reduced expression, altered redistribution and defective recruitment of GLUT4. We show here an association of the latter defect with alterations at the level of Small GTP-binding proteins possibly leading to an impaired trafficking of GLUT4 in the insulin-resistant state.
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insulin induced translocation of the glucose transporter glut4 in cardiac muscle studies on the role of Small Molecular Mass gtp binding proteins
Biochemical Journal, 1994Co-Authors: Ingo Uphues, T Kolter, B Goud, Jurgen EckelAbstract:Subcellular fractions obtained from rat cardiac ventricular tissue were used to elucidate a possible functional relationship between Small-Molecular-Mass G-proteins and the insulin-responsive glucose transporter GLUT4. Proteins were separated by SDS/PAGE and transferred to nitrocellulose membranes. Incubation with [alpha-32P]GTP revealed the presence of two major distinct GTP-binding protein bands of 24 and 26 kDa in both plasma and microsomal membranes. Immunoadsorption of microsomal membranes to anti-GLUT4 antibodies was used to isolate GLUT4-enriched membrane vesicles. This material was found to contain a much decreased amount of Small G-proteins, with the exclusive presence of the 24 kDa species. Insulin treatment in vivo had no effect on the microsomal membrane content of Small GTP-binding proteins, but significantly decreased the 24 kDa species in GLUT4-enriched vesicles by 36 +/- 5% (n = 3). This correlated with a decreased (30-40%) recovery of GLUT4-enriched vesicles from insulin-treated animals. Western-blot analysis of microsomal membranes with a panel of antisera against rab GTP-binding proteins indicated the presence of rab4A, with a Molecular Mass of 24 kDa, whereas rab1A, rab2 and rab6 were not observed. rab4A was barely detectable in GLUT4-enriched vesicles; however, insulin produced an extensive shift of rab4A from the cytosol and the microsomal fraction to the plasma membrane with a parallel increase in GLUT4. These data show that a Small GTP-binding protein is co-localized with GLUT4 in an insulin-responsive intracellular compartment, and strongly suggest that this protein is involved in the exocytosis of GLUT4 in cardiac muscle. Furthermore, the observed translocation of rab4A is compatible with insulin-induced endosome recycling processes, possibly including the glucose transporters.
Milan N. Šarevski - One of the best experts on this subject based on the ideXlab platform.
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Water (R718) Centrifugal Compressors
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Influence of the refrigerant thermodynamic properties on the characteristics of centrifugal compressors is investigated. Peculiarities of centrifugal compressors working with various refrigerants are defined and the range of priority application is determined. Interdependence between centrifugal stage pressure ratio, peripheral Mach number and impeller peripheral speed, as well as the influence of the refrigeration capacity on the dimensions of centrifugal compressors are determined to obtain the range of reasonable usage of R718 refrigeration/heat pump systems. Deep vacuum operating conditions, low specific volumetric cooling capacity of R718, and Small Molecular Mass of water are the peculiarities that determine the main parameters of the water (R718) centrifugal compressors and the range of rational application of the R718 centrifugal refrigeration/heat pump systems. The high peripheral impeller speed, high Mach number, and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the compressor flow field.
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Water (R718) Turbo Compressor Refrigeration/Heat Pump Systems
Water (R718) Turbo Compressor and Ejector Refrigeration Heat Pump Technology, 2020Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:R718 centrifugal refrigeration/heat pump systems are investigated to determine optimal schematic structure, to estimate performance characteristics, and to provide possibilities for wider application in the field of air-conditioning. Deep vacuum operating conditions, low specific volumetric cooling capacity, Small Molecular Mass, and high isentropic exponent of the water are peculiarities which determine the main parameters of centrifugal compressors and the range of rational application of R718 refrigeration/heat pump systems. High impeller peripheral speed, high Mach number, low Reynolds number, large dimensions, and high superheating at the compressor discharge are the features of R718 centrifugal refrigeration compressors. A two-stage centrifugal compressor and, respectively, two-stage refrigeration cycle are optimal technical solutions for refrigeration systems in the field of air-conditioning applications. Direct flash evaporation and condensation provide simplicity and the possibility of achieving a high COP. A comparison shows that R718 centrifugal refrigeration systems are competitive with traditional refrigeration systems.
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Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Abstract The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with Small Molecular Mass of the water and high isentropic exponent, result on high impeller peripheral speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons.
-
Preliminary study of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector
International Journal of Refrigeration, 2014Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:The paper describes the investigations of a novel R718 refrigeration cycle with single stage centrifugal compressor and two-phase ejector as a second stage compression device. The limitations of the R718 centrifugal stage pressure ratio, connected with Small Molecular Mass of the water and high isentropic exponent, result on high impeller peripheral speed, high Mach number and high discharge temperature. Reynolds number is low and dimensions of the compressor stage are large. The complex thermal and flow phenomena inside two-phase ejector flow field are investigated and performance characteristics are estimated. Although efficiency of the concept of compression with hydraulic pump and two-phase ejectors is lower, the integration of two-phase ejectors in the R718 centrifugal unit results in low cost high capacity refrigeration system with high energy efficiency, competitive with traditional refrigeration systems by environmental, technical and economical reasons. © 2013 Elsevier Ltd and IIR. All rights reserved.
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Characteristics of water vapor turbocompressors applied in refrigeration and heat pump systems
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Milan N. Šarevski, Vasko N. ŠarevskiAbstract:Abstract Interdependence between centrifugal stage pressure ratio, peripheral Mach number and impeller peripheral speed, as well the influence of the refrigerating capacity on the dimensions of the centrifugal compressor are determined to obtain the range of reasonable usage of R718 refrigerating/heat pump systems. The deep vacuum operating conditions, the low specific volumetric cooling capacity of the R718 and the Small Molecular Mass of the water are the peculiarities which determined the main parameters of the centrifugal compressor and the range of rational application of the R718 refrigerating/heat pump systems. The high peripheral impeller speed, high Mach number and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the compressor flow field. Estimation of the flow characteristics and of the performance characteristics of the water vapor centrifugal compressors is presented, using results of CFD simulations and experimental investigations for high pressure ratio centrifugal compressors.
Ingo Uphues - One of the best experts on this subject based on the ideXlab platform.
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Insulin-dependent translocation of the Small GTP-binding protein rab3C in cardiac muscle: studies on insulin-resistant Zucker rats
FEBS Letters, 1995Co-Authors: Ingo Uphues, Yijuang Chern, Jurgen EckelAbstract:Abstract The failure of insulin-regulated recruitment of the GLUT4 glucose transporter in cardiac muscle of obese Zucker rats is associated with alterations of the subcellular distribution of the Small-Molecular-Mass GTP-binding protein rab4A. Here, we show by subcellular fractionation and Western blotting a translocation of the Small-Molecular-Mass GTP-binding protein rab3C from microsomal membranes to plasma membranes in lean control rats following in vivo insulin stimulation. However, in cardiac muscle of obese animals no significant effect of the hormone on the subcellular distribution of rab3C was observed. In GLUT4-enriched membrane vesicles, obtained from cardiac microsomes of the obese group as well as of lean controls, rab3C was not detectable. It is suggested that the altered behaviour of rab3C may contribute to an impaired trafficking of GLUT4 in the insulin-resistant state.
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failure of insulin regulated recruitment of the glucose transporter glut4 in cardiac muscle of obese zucker rats is associated with alterations of Small Molecular Mass gtp binding proteins
Biochemical Journal, 1995Co-Authors: Ingo Uphues, T Kolter, B Goud, Jurgen EckelAbstract:Cardiac ventricular tissue of lean and genetically obese (fa/fa) Zucker rats was used to study the expression, subcellular distribution and insulin-induced recruitment of the glucose transporter GLUT4 and to elucidate possible Molecular alterations of the translocation process. Hearts were removed from basal and insulin-treated (20 min) lean and obese Zucker rats, and processed for subcellular fractionation and Western blotting of proteins. In obese rats, the total GLUT4 content in a crude membrane fraction was reduced to 75 +/- 8% (P = 0.019) of lean controls. In contrast, GLUT4 abundance in plasma membranes was not significantly different between lean and obese rats with a concomitant decrease (47 +/- 3%) in the microsomal fraction of obese animals. In plasma membranes of lean animals insulin was found to increase the GLUT4 abundance to 294 +/- 43% of control with a significantly (P = 0.009) reduced effect in the obese group (139 +/- 10% of control). In these animals insulin failed to recruit GLUT4 from the microsomal fraction, whereas the hormone induced a significant decrease (41 +/- 4%) of microsomal GLUT4 in lean controls. In GLUT4-enriched membrane vesicles, obtained from cardiac microsomes of lean rats, a 24 kDa GTP-binding protein could be detected, whereas no significant labelling of this species was observed in GLUT4 vesicles prepared from obese animals. In addition to the translocation of GLUT4, insulin was found to promote the movement of the Small GTP-binding protein rab4A from the cytosol (decrease to 61 +/- 13% of control) to the plasma membrane (increase to 177 +/- 19% of control) in lean rats with no effect of the hormone on rab4A redistribution in the obese group. In conclusion, cardiac glucose uptake of insulin-resistant obese Zucker rats is subject to multiple cellular abnormalities involving a reduced expression, altered redistribution and defective recruitment of GLUT4. We show here an association of the latter defect with alterations at the level of Small GTP-binding proteins possibly leading to an impaired trafficking of GLUT4 in the insulin-resistant state.
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Insulin-dependent of the Small GTP-binding protein rab3C in cardiac muscle: studies on insulin-resistant Zucker rats
1995Co-Authors: Ingo Uphues, Yijuang Chern, Jfirgen EckelAbstract:The failure of insufin-regulated recruitment of the GLUT4 glucose transporter in cardiac muscle of obese Zucker rats is associated with alterations of the subcellular distribution of the Small-Molecular-Mass GTP-binding protein rab4A. Here, we show by subcellular fractionation and Western blotting a translocation of the smull-Molecular-Mass GTP-binding protein rab3C from microsomul membranes to plasma membranes in lean control rats following in vivo insulin stimulation. However, in cardiac muscle of obese animals no significant effect of the hormone on the subcellular distribution of rab3C was observed. In GLUT4-enriched membrane vesicles, obtained from cardiac microsomes of the obese group as well as of lean controls, rab3C was not detectable. It is suggested that the altered behaviour of rah3C may contribute to an impaired trafficking of GLUT4 in the insulin-resistant K~y words: Small GTP-binding protein; Rab3; Cardiac muscle; Insulin resistance; Zucker rat
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insulin induced translocation of the glucose transporter glut4 in cardiac muscle studies on the role of Small Molecular Mass gtp binding proteins
Biochemical Journal, 1994Co-Authors: Ingo Uphues, T Kolter, B Goud, Jurgen EckelAbstract:Subcellular fractions obtained from rat cardiac ventricular tissue were used to elucidate a possible functional relationship between Small-Molecular-Mass G-proteins and the insulin-responsive glucose transporter GLUT4. Proteins were separated by SDS/PAGE and transferred to nitrocellulose membranes. Incubation with [alpha-32P]GTP revealed the presence of two major distinct GTP-binding protein bands of 24 and 26 kDa in both plasma and microsomal membranes. Immunoadsorption of microsomal membranes to anti-GLUT4 antibodies was used to isolate GLUT4-enriched membrane vesicles. This material was found to contain a much decreased amount of Small G-proteins, with the exclusive presence of the 24 kDa species. Insulin treatment in vivo had no effect on the microsomal membrane content of Small GTP-binding proteins, but significantly decreased the 24 kDa species in GLUT4-enriched vesicles by 36 +/- 5% (n = 3). This correlated with a decreased (30-40%) recovery of GLUT4-enriched vesicles from insulin-treated animals. Western-blot analysis of microsomal membranes with a panel of antisera against rab GTP-binding proteins indicated the presence of rab4A, with a Molecular Mass of 24 kDa, whereas rab1A, rab2 and rab6 were not observed. rab4A was barely detectable in GLUT4-enriched vesicles; however, insulin produced an extensive shift of rab4A from the cytosol and the microsomal fraction to the plasma membrane with a parallel increase in GLUT4. These data show that a Small GTP-binding protein is co-localized with GLUT4 in an insulin-responsive intracellular compartment, and strongly suggest that this protein is involved in the exocytosis of GLUT4 in cardiac muscle. Furthermore, the observed translocation of rab4A is compatible with insulin-induced endosome recycling processes, possibly including the glucose transporters.
Chang An Yu - One of the best experts on this subject based on the ideXlab platform.
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cloning gene sequencing and expression of the Small Molecular Mass ubiquinone binding protein of mitochondrial ubiquinol cytochrome c reductase
Journal of Biological Chemistry, 1995Co-Authors: Linda Yu, Kaiping Deng, Chang An YuAbstract:Abstract The cDNA encoding QPc-9.5 kDa (subunit VII) of bovine heart mitochondrial ubiquinol-cytochrome c reductase was cloned and sequenced. This cDNA is 665 base pairs long with an open reading frame of 246 base pairs that encodes an 81-amino acid mature QPc-9.5 kDa. The insert contains 395 base pairs of a 3′-noncoding sequence with a poly(A) tail. The amino acid sequence of QPc-9.5 kDa deduced from this nucleotide sequence is the same as that obtained by protein sequencing except that residue 61 is tryptophan instead of cysteine. The QPc-9.5 kDa was overexpressed in Escherichia coli JM109 cells as a glutathione S-transferase fusion protein (GST-QPc) using the expression vector, pGEX/QPc. The yield of soluble active recombinant GST-QPc fusion protein depends on the induction growth time, temperature, and medium. Maximum yield of recombinant fusion protein was obtained from cells harvested 3 h postinduction of growth at 27°C on LB medium containing betaine and sorbitol. QPc-9.5 kDa was released from the fusion protein by proteolytic cleavage with thrombin. Isolated recombinant QPc-9.5 kDa showed one protein band in SDS-polyacrylamide gel electrophroesis corresponding to subunit VII of mitochondrial ubiquinol-cytochrome c reductase. Although the isolated recombinant QPc-9.5 kDa is soluble in aqueous solution, it is in a highly aggregated form, with an apparent Molecular Mass of over 1 million. Addition of detergent deaggreates the isolated protein to the monomeric state, suggesting that the recombinant protein exists as a hydrophobic aggregation in aqueous solution. The recombinant QPc-9.5 kDa binds ubiquinone and shows 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 the recombinant protein may be in the functionally active state.
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the Small Molecular Mass ubiquinone binding protein qpc 9 5 kda in mitochondrial ubiquinol cytochrome c reductase isolation ubiquinone binding domain and immunoinhibition
Biochemistry, 1990Co-Authors: Shigeyuki Usui, Linda Yu, Chang An YuAbstract:: The Small Molecular Mass ubiquinone-binding protein (QPc-9.5 kDa) was purified to homogeneity from 3-azido-2-methyl-5-methoxy-6-(3,7-dimethyl[3H]octyl)-1,4-benzoquinol+ ++- labeled bovine heart mitochondrial ubiquinol-cytochrome c reductase. The N-terminal amino acid sequence of the isolated protein is Gly-Arg-Gln-Phe-Gly-His-Leu-Thr-Arg-Val-Arg-His-, which is identical with that of a Mr = 9500 protein in the reductase [Borchart et al. (1986) FEBS Lett. 200, 81-86]. A ubiquinone-binding peptide was prepared from [3H]azidoubiquinol-labeled QPc-9.5 kDa protein by trypsin digestion followed by HPLC separation. The partial N-terminal amino acid sequence of this peptide, Val-Ala-Pro-Pro-Phe-Val-Ala-Phe-Tyr-Leu-, corresponds to amino acid residues 48-57 in the reported Mr = 9500 protein. According to the proposed structural model for the Mr = 9500 protein, the azido-Q-labeled peptide is located in the membrane on the matrix side. These results confirm our previous assessment that the Mr = 13,400 subunit is not the Small Molecular weight Q-binding protein. Purified antibodies against QPc-9.5 kDa have a high titer with isolated QPc-9.5 kDa protein and complexes that contain it. Although antibodies against QPc-9.5 kDa do not inhibit intact succinate- and ubiquinol-cytochrome c reductases, a decrease of 85% and 20% in restoration of succinate- and ubiquinol-cytochrome c reductases, respectively, is observed when delipidated succinate- or ubiquinol-cytochrome reductases are incubated with antibodies prior to reconstitution with ubiquinone and phospholipid, indicating that epitopes at the catalytic site of QPc-9.5 kDa are buried in the phospholipid environment.(ABSTRACT TRUNCATED AT 250 WORDS)
