scholarly journals Single-Turnover Kinetics of Methyl Transfer to tRNA by Methyltransferases

2016 ◽  
pp. 79-96
Author(s):  
Ya-Ming Hou
Keyword(s):  
Single Turnover ◽  
Methyl Transfer ◽  
Kinetics Of

Conformational Changes of the Membrane-Bound ATPase of Bacterial Chromatophores Revealed by Fluorescence Changes of Fluorescamine-Labelled Coupling Factors

1978 ◽  
Vol 33 (5-6) ◽  
pp. 421-427
Author(s):  
Peter Gräber ◽  
Sathamm Saphon
Keyword(s):  
Conformational Changes ◽  
Fluorescence Emission ◽  
Continuous Light ◽  
Coupling Factor ◽  
Single Turnover ◽  
Fluorescence Change ◽  
Transfer Inhibitor ◽  
Membrane Bound ◽  
Coupling Factors ◽  
Kinetics Of

Abstract The solubilized coupling factor (F1) of Rps. sphaeroides chromatophores was allowed to react with fiuorescamine which led to a fluorescence labelled F1 . After reconstitution with the depleted membranes the fluorescence-labelled F1 was shown to restore photophosphorylation in continuous light in a similar way to the non-labelled F1 . In parallel, a decrease of the fluorescence emission of the labelled and reconstituted coupling factor was observed. The solubilized and labelled F1 showed also a fluorescence decrease as the polarity of the medium was increased. In single turnover flashes the fluorescence change was found to be inhibited by an uncoupling agent such as FCCP. The kinetics of the change were sensitive to phosphorylating agents and to an “energy transfer inhibitor” such as venturicidin. It is suggested that the observed fluorescence changes reflect conformational changes of the ATPase enzyme complex.

On the mechanism of NADP + -linked isocitrate dehydrogenase from heart mitochondria. II. The transient-state kinetics of the oxidative decarboxylation of isocitrate

1982 ◽  
Vol 214 (1196) ◽  
pp. 389-402 ◽  
Keyword(s):  
Preceding Paper ◽  
Transient State ◽  
Oxidative Decarboxylation ◽  
Single Turnover ◽  
Fluorescence Measurements ◽  
Decarboxylation Reaction ◽  
Flow Apparatus ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Absorption Measurements

The kinetics of a single turnover of enzyme-catalysed oxidative decarboxylation have been studied by mixing a stoichiometric complex of enzyme, isocitrate and Mg 2+ with large concentrations of NADP + in a stopped-flow apparatus, and monitoring the formation of NADPH by fluorescence measurements. A transient is revealed that exhibits enhanced nucleotide fluorescence and is not detectable by light absorption measurements. The results obtained with the largest NADP + concentrations, such that the product NADPH is largely displaced from its enzyme complex, show that a step that precedes the release of free NADPH is rate-limiting in the oxidative decarboxylation reaction under conditions of catalytic cycling. The rate constants for this step, tentatively identified as the formation of the complex of enzyme, Mg 2+ and NADPH from a precursor NADPH-containing complex, and for the dissociation of NADPH from this complex have been estimated from the integrated rate equation for a simple model for the product phase of the reaction, by methods of nonlinear regression analysis. In line with the conclusions from the preceding paper, it is suggested that formation of an abortive complex of enzyme, Mg 2+ , isocitrate and NADPH under catalytic cycling conditions serves to by-pass the potentially rate-limiting dissociation of NADPH from the enzyme-Mg 2+ -NADPH complex.

Multichannel Analysis of Single-Turnover Kinetics of Cytochromeaa3Reduction of O2

Biochemistry ◽  
1997 ◽  
Vol 36 (9) ◽  
pp. 2439-2449 ◽  
Author(s):  
Salil Bose ◽  
Richard W. Hendler ◽  
Richard I. Shrager ◽  
Sunney I. Chan ◽  
Paul D. Smith
Keyword(s):  
Single Turnover ◽  
Multichannel Analysis ◽  
Kinetics Of

Single-turnover kinetics of 2,3-dihydroxybiphenyl 1,2-dioxygenase reacting with 3-formylcatechol

2005 ◽  
Vol 338 (1) ◽  
pp. 223-229 ◽  
Author(s):  
Tetsuo Ishida ◽  
Toshiya Senda ◽  
Hiroyuki Tanaka ◽  
Atsushi Yamamoto ◽  
Kihachiro Horiike
Keyword(s):  
Single Turnover ◽  
Kinetics Of

scholarly journals Regulatory role of the respiratory supercomplex factors in Saccharomyces cerevisiae

2016 ◽  
Vol 113 (31) ◽  
pp. E4476-E4485 ◽  
Author(s):  
Camilla Rydström Lundin ◽  
Christoph von Ballmoos ◽  
Martin Ott ◽  
Pia Ädelroth ◽  
Peter Brzezinski
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Electron Transfer ◽  
Ligand Binding ◽  
Structural Changes ◽  
Regulatory Mechanism ◽  
Supramolecular Interactions ◽  
Wild Type ◽  
Single Turnover ◽  
Kinetics Of

The respiratory supercomplex factors (Rcf) 1 and 2 mediate supramolecular interactions between mitochondrial complexes III (ubiquinol-cytochrome c reductase; cyt. bc1) and IV (cytochrome c oxidase; CytcO). In addition, removal of these polypeptides results in decreased activity of CytcO, but not of cyt. bc1. In the present study, we have investigated the kinetics of ligand binding, the single-turnover reaction of CytcO with O2, and the linked cyt. bc1-CytcO quinol oxidation-oxygen-reduction activities in mitochondria in which Rcf1 or Rcf2 were removed genetically (strains rcf1Δ and rcf2Δ, respectively). The data show that in the rcf1Δ and rcf2Δ strains, in a significant fraction of the population, ligand binding occurs over a time scale that is ∼100-fold faster (τ ≅ 100 μs) than observed with the wild-type mitochondria (τ ≅ 10 ms), indicating structural changes. This effect is specific to removal of Rcf and not dissociation of the cyt. bc1–CytcO supercomplex. Furthermore, in the rcf1Δ and rcf2Δ strains, the single-turnover reaction of CytcO with O2 was incomplete. This observation indicates that the lower activity of CytcO is caused by a fraction of inactive CytcO rather than decreased CytcO activity of the entire population. Furthermore, the data suggest that the Rcf1 polypeptide mediates formation of an electron-transfer bridge from cyt. bc1 to CytcO via a tightly bound cyt. c. We discuss the significance of the proposed regulatory mechanism of Rcf1 and Rcf2 in the context of supramolecular interactions between cyt. bc1 and CytcO.

Single-turnover kinetics of helicase-catalyzed DNA unwinding monitored continuously by fluorescence energy transfer

Biochemistry ◽  
1994 ◽  
Vol 33 (47) ◽  
pp. 14306-14316 ◽  
Author(s):  
Keith P. Bjornson ◽  
Mohan Amaratunga ◽  
Keith J. M. Moore ◽  
Timothy M. Lohman
Keyword(s):  
Energy Transfer ◽  
Dna Unwinding ◽  
Fluorescence Energy Transfer ◽  
Single Turnover ◽  
Kinetics Of ◽  
Fluorescence Energy
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