scholarly journals Turbulence Decay in Stopped Flow Experiments by Measurements of Electric Dichroism

2000 ◽  
Vol 104 (5) ◽  
pp. 1115-1121 ◽  
Author(s):  
Dietmar Porschke
Keyword(s):  
Stopped Flow ◽  
Turbulence Decay ◽  
Electric Dichroism ◽  
Flow Experiments

A stopped-flow electric dichroism study on adsorption of metal chelates by a colloidal clay

1990 ◽  
Vol 94 (15) ◽  
pp. 5896-5900 ◽  
Author(s):  
Masahiro. Taniguchi ◽  
Masami. Kaneyoshi ◽  
Yuji. Nakamura ◽  
Akihiko. Yamagishi ◽  
Toschitake. Iwamoto
Keyword(s):  
Metal Chelates ◽  
Stopped Flow ◽  
Electric Dichroism ◽  
Colloidal Clay

Calsequestrin is essential for the Ca2+ release induced by myotoxin α in skeletal muscle sarcoplasmic reticulum

1995 ◽  
Vol 73 (8) ◽  
pp. 1181-1185 ◽  
Author(s):  
Masamichi Ohkura ◽  
Ken-Ichi Furukawa ◽  
Yasushi Ohizumi ◽  
Tory Ide ◽  
Takashi Kawasaki ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Channel Blocker ◽  
Single Channel ◽  
Heavy Fraction ◽  
Stopped Flow ◽  
Single Channel Recording ◽  
Excitatory Effect ◽  
Crotalus Viridis ◽  
Channel Currents ◽  
Flow Experiments

Myotoxin α (MYTX), a polypeptide toxin purified from the venom of prairie rattlesnakes (Crotalus viridis viridis), induced Ca2+ release from the heavy fraction of skeletal sarcoplasmic reticulum (HSR), using a Ca2+ electrode. The effect of MYTX was nearly abolished by pretreatment with ryanodine, an alkaloid-based Ca2+ channel blocker. In the stopped-flow experiments, MYTX increased the choline+ permeability of HSR in the presence of calsequestrin (CS). Single channel recording experiments showed that in the presence of CS, the channel currents were markedly enhanced by MYTX applied to the cis side, but not to the trans side. However, in the absence of CS, MYTX failed to cause the excitatory effect in both the experiments. These results suggest that CS is essential for MYTX-induced Ca2+ release through the Ca2+ release channels in skeletal HSR.Key words: calsequestrin, myotoxin α, Ca2+ release, Ca2+ release channels, sarcoplasmic reticulum.

Use of Viscogens, dNTPαS, and Rhodium(III) as Probes in Stopped-Flow Experiments To Obtain New Evidence for the Mechanism of Catalysis by DNA Polymerase β†,‡

Biochemistry ◽  
2005 ◽  
Vol 44 (13) ◽  
pp. 5177-5187 ◽  
Author(s):  
Marina Bakhtina ◽  
Soojin Lee ◽  
Yu Wang ◽  
Chris Dunlap ◽  
Brandon Lamarche ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Stopped Flow ◽  
Dna Polymerase Β ◽  
Mechanism Of Catalysis ◽  
New Evidence ◽  
Flow Experiments

The dependence of the rates of reduction of cobalt(III)-μ-peroxo complexes on isomeric structure

1984 ◽  
Vol 62 (11) ◽  
pp. 2127-2130 ◽  
Author(s):  
Steve C. F. Au-Yeung ◽  
Donald R. Eaton
Keyword(s):  
Rate Constants ◽  
Chemical Shifts ◽  
Cobalt Complex ◽  
Stopped Flow ◽  
Ferrous Ions ◽  
Point Charge Model ◽  
Isomeric Structure ◽  
Initial Reduction ◽  
Charge Model ◽  
Flow Experiments

The reaction of μ-peroxybis(ethylenediamine)bis(diethylenetriamine)cobalt(III) with ferrous ions has been studied by stopped flow spectrophotometry and by 59Co nmr. Two separate initial reduction steps with second order rate constants of 1.07 and 3.04 M−1 s−1, respectively, can be discerned in the stopped flow experiments. These two rate constants are assigned to inner sphere reduction of the aef,cd,b and edf,ac,b isomers of the peroxy cobalt complex, respectively. The different isomers can be distinguished by 59Co nmr. If there is insufficient Fe2+ present to completely reduce the complex to Co(II) and water, the change in the relative intensities of the 59Co resonances after partial reduction shows that one isomer has reacted faster than the other. The 59Co resonances can be assigned to the different isomers on the basis of a point charge model for the chemical shifts and line widths. Based on this model it is concluded that the isomer with the central NH of the diethylenetriamine trans to the peroxy ligand reacts faster. This result is compared to literature reports on the relative rates of substitution of isomers of Co(III) complexes with ethylenediamine and diethylenetriamine ligands.

scholarly journals Effects of Mg2+, Ca2+ and Mn2+ on sheep liver cytoplasmic aldehyde dehydrogenase

1982 ◽  
Vol 205 (2) ◽  
pp. 443-448 ◽  
Author(s):  
F M Dickinson ◽  
G J Hart
Keyword(s):  
Aldehyde Dehydrogenase ◽  
Esterase Activity ◽  
Metal Ion ◽  
Stopped Flow ◽  
Maximal Effect ◽  
Ion Concentrations ◽  
Sheep Liver ◽  
High Concentrations ◽  
Flow Experiments ◽  
Active Centres

Sheep liver cytoplasmic aldehyde dehydrogenase is strongly inhibited by Mg2+, Ca2+ and Mn2+. The inhibition is only partial, however, with 8-15% of activity remaining at high concentrations of these agents. In 50 mM-Tris/Hcl, pH 7.5, the concentrations giving half-maximal effect were: Mg2+, 6.5 micrometers; Ca2+, 15.2 micrometers; Mn2+, 1.5 micrometer. The esterase activity of the enzyme is not affected by such low metal ion concentrations, but appears to be activated by high concentrations. Fluorescence-titration and stopped-flow experiments provide evidence for interaction of Mg2+ with NADH complexes of the enzyme. As no evidence for the presence of increased concentrations of functioning active centres was obtained in the presence of Mg2+, it is concluded that effects of Mg2+ (and presumably Ca2+ and Mn2+ also) are brought about by trapping increased concentrations of NADH in a Mg2+-containing complex. This complex must liberate products more slowly than any of the complexes involved in the non-inhibited mechanism.

scholarly journals Investigation of the electron-transfer properties of cytochrome c oxidase covalently cross-linked to Fe- or Zn-containing cytochrome c

1992 ◽  
Vol 287 (3) ◽  
pp. 951-956 ◽  
Author(s):  
T A Alleyne ◽  
M T Wilson ◽  
G Antonini ◽  
F Malatesta ◽  
B Vallone ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Redox Properties ◽  
Cross Linking ◽  
Stopped Flow ◽  
Steady State Levels ◽  
Electron Transfer Properties ◽  
Transfer Properties ◽  
Flow Experiments ◽  
Covalent Complex

Complexes of cytochrome c oxidase and cytochrome c (Fe- or Zn-containing) have been prepared by 1-ethyl-3-[3-(dimethylamino)propyl]carbodi-imide (EDC) cross-linking. The site to which the cytochrome c covalently binds has been identified as being the same, or close to, the site occupied by cytochrome c in the electrostatic complex which may be formed between the proteins. Stopped-flow experiments, monitored either at a single wavelength or through a rapid wavelength-scan facility, showed that covalently bound Fe-containing cytochrome c cannot donate electrons to cytochrome a. Free Fe-containing cytochrome c was, however, able to transfer electrons to cytochrome a in covalent complexes containing either Fe- or Zn-containing cytochrome c. Turnover experiments showed that the complexed enzyme remains catalytically competent but with decreased (40-80%) activity. The steady-state levels of reduction of both free cytochrome c and cytochrome a in the covalent complex were higher than found in the control (uncomplexed) enzyme. These results are discussed with reference to the structure of the covalent complex and lead us to conclude that cytochrome a may accept electrons directly from free cytochrome c and that cross-linking impairs the redox properties of the CuA site.

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