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981.
982.
Tiron as a spin-trap for superoxide radicals produced by the respiratory chain of submitochondrial particles 总被引:1,自引:0,他引:1
I V Grigolava M Iu Ksenzenko A A Konstantinob A N Tikhonov T M Kerimov 《Biokhimii?a (Moscow, Russia)》1980,45(1):75-82
Tiron can be used as a spin-trap for O2 radicals generated by the respiratory chain of submitochondrial particles (SMP). Using this sensitive method, it was shown that the O2 (radical) production by the succinate-oxidizing SMP can be reduced by antimycin or 4-nonyl-2-hydroxyquinoline-N-oxide, the effects of both antibiotics being abolished and prevented by cyanide. It is suggested tht the O2 radicals are produced due to autooxidation of ubisemiquinone which is formed as an intermediate upon one-electron oxidation of CoQH2 by cytochrome c1. The effects of antimycin, 2-nonyl-4-hydroxyquinoline-N-oxide and cyanide on the O2 (radical) generation correlate with the effects of these inhibitors on a steady-state concentration of ubisemiquinone predicted by the Mitchell's Q-cycle hypothesis. 相似文献
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984.
The effects of cAMP-dependent protein kinase (cAMP-PK) phosphorylation on the degradation of the microtubule-associated protein tau by calpain were studied. Purified bovine brain tau that had been phosphorylated by cAMP-PK had a slower migration pattern on sodium dodecyl sulfate-polyacrylamide gels and a more acidic, less heterogeneous pattern on two-dimensional, nonequilibrium pH gradient electrophoresis (NEPHGE) gels compared with untreated tau. Phosphorylation of tau by cAMP-PK significantly inhibited its proteolysis by calpain compared with untreated tau. To our knowledge this is the first demonstration that phosphorylation of tau by a specific kinase results in increased resistance to hydrolysis by calpain. Tau dephosphorylated by alkaline phosphatase migrated more rapidly on sodium dodecyl sulfate-polyacrylamide gels and also showed an altered two-dimensional NEPHGE pattern. Dephosphorylation of tau had no effect on its susceptibility to calpain proteolysis, indicating that regulation of the susceptibility to calpain hydrolysis is due to the phosphorylation of a specific site(s). These results suggest a role for phosphorylation in regulating the degradation of tau. Abnormal phosphorylation could result in a protease-resistant tau population which may contribute to the formation of paired helical filaments in Alzheimer's disease. 相似文献
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A N Siniakov O I Serpinski? N K Daniliuk V E Chizhikov S Kh Degtiarev 《Bioorganicheskaia khimiia》1989,15(5):638-647
For preparing a DNA fragment with unique protruding ends, plasmid vectors pMB123 and pMB124 were constructed by inserting a synthetic polylinker into plasmid pUR222 at the EcoRI-PstI sites. The polylinker contains two FokI and HgaI sites at its ends in opposite orientation flanking a combination of SalGI, AccI, HindII, HindIII (the latter site is absent from pMB124) and BamHI sites. DNA fragment cloned at the SalGI and BamHI sites can be regenerated by either FokI or HgaI treatment, the SalGI and BamHI sites being deleted from the cloned sequence. Fragments coding for parts of human interleukin-2 were cloned in these vectors. 相似文献
990.