Phosphate-Transferring Enzymes

Dixon, Malcolm; Webb, Edwin C.

doi:10.1093/oxfordjournals.bmb.a074324

Cited by 29 publications

(39 citation statements)

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“…We reconcile these two observations by identifying the parameter regime where our theoretically derived f (t) is, indeed, well approximated by difference of two exponentials [7,8,9,10,11]. Moreover, we show that t −1 , inverse of the mean dwell time, satisfies a Michaelis-Menten-like equation [12]. The reason for this feature of the mean dwell time is traced to the close formal similarity between the mechanochemical cycle of a ribosome and the catalytic cycle in the Michaelis-Menten theory of enzymes [12].…”

Section: Introductionsupporting

confidence: 72%

“…Moreover, we show that t −1 , inverse of the mean dwell time, satisfies a Michaelis-Menten-like equation [12]. The reason for this feature of the mean dwell time is traced to the close formal similarity between the mechanochemical cycle of a ribosome and the catalytic cycle in the Michaelis-Menten theory of enzymes [12].…”

Section: Introductionmentioning

confidence: 74%

“…One remarkable feature of the expression (24) is that it is very similar to the Michaelis-Menten equation (MM equation) for the speed of enzymatic reactions in bulk [12]. In chemical kinetics the MM equation is derived for the enzymatic cycle shown in fig.4 where the enzyme E enhances the rate of the reaction that converts the substrates S into the product P .…”

Section: Mean Dwell Time: Michaelis-menten Equation?mentioning

confidence: 97%

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Stochastic kinetics of ribosomes: Single motor properties and collective behavior

Garai

Chowdhury

et al. 2009

Phys. Rev. E

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Synthesis of protein molecules in a cell are carried out by ribosomes. A ribosome can be regarded as a molecular motor which utilizes the input chemical energy to move on a messenger RNA (mRNA) track that also serves as a template for the polymerization of the corresponding protein. The forward movement, however, is characterized by an alternating sequence of translocation and pause. Using a quantitative model, which captures the mechanochemical cycle of an individual ribosome, we derive an exact analytical expression for the distribution of its dwell times at the successive positions on the mRNA track. Inverse of the average dwell time satisfies a "Michaelis-Menten-like" equation and is consistent with the general formula for the average velocity of a molecular motor with an unbranched mechano-chemical cycle. Extending this formula appropriately, we also derive the exact force-velocity relation for a ribosome. Often many ribosomes simultaneously move on the same mRNA track, while each synthesizes a copy of the same protein. We extend the model of a single ribosome by incorporating steric exclusion of different individuals on the same track. We draw the phase diagram of this model of ribosome traffic in 3-dimensional spaces spanned by experimentally controllable parameters. We suggest new experimental tests of our theoretical predictions.

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Section: Introductionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 74%

Section: Mean Dwell Time: Michaelis-menten Equation?mentioning

confidence: 97%

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Stochastic kinetics of ribosomes: Single motor properties and collective behavior

Garai

Chowdhury

et al. 2009

Phys. Rev. E

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“…To which extent they reflect intrinsic ionizations of functional groups at the active center of the enzyme cannot be deduced from the present data. In general, such pH profiles of enzymatic activities include also the contributions of pH dependent kinetic terms (Dixon and Webb, 1979).…”

Section: Partial Kinetic Characterization Of the P14g Mutant Proteinmentioning

confidence: 99%

Studies with Lysine N6-Hydroxylase. Effect of a Mutation in the Assumed FAD Binding Site on Coenzyme Affinities and on Lysine Hydroxylating Activity

Stehr

Smau

Singh³

et al. 1999

Biological Chemistry

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-hydroxylase (EC 1.14.13.99) exhibits an unusual proline in a position where a highly conserved glycine is found in other FAD dependent hydroxylases. We have studied the role of this proline by mutating it to glycine in [P14G]aerA, which was expressed in Escherichia coli M15-2 and purified to homogeneity. The mutation has marked effects on the affinities of the cofactors FAD and NADPH as well as the substrate, lysine. Compared to the wild-type enzyme, the activity vs. pH profile of the mutant protein indicates a shift of the apparent pK' a s (7.8 and 8.7 for wild-type and 6.8 and 7.7 for the P14G-mutant enzyme) and of the activity maximum (pH 8 for wild-type and pH 7 for the P14G-mutant enzyme). While the activity of the mutant enzyme is much lower under conditions found to be optimal for the wild-type enzyme, adjustment of substrate and cofactor concentrations and pH leads to comparable activities for the mutant enzyme. These results suggest that the proline fulfils an important structural role in the proposed FAD binding site.

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“…Because of substrate depletion, however, reaction rates became nonlinear with respect to time when the concentration of F-1,6-P2 was <10 ¢tM. For Km(F-1,6-P2) determinations, reaction rates were therefore estimated by the slopes of tangents drawn on the progress curve, as described by Dixon and Webb [13]. These tangents represent the reaction rates at the corresponding concentrations of substrate remaining [13].…”

Section: Enzyme Assay and Purificationmentioning

confidence: 99%

Effect of polyethylene glycol on the activity, intrinsic fluorescence, and oligomeric structure of castor seed cytosolic fructose‐1, 6‐bisphosphatase

1995

FEBS Letters

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The effect of polyethylene glycol (PEG) on the activity, intrinsic fluorescence, and oligomeric structure of homogeneous cytosolic fructose-l,6-bisphosphatase (FBPasec) from endosperm of germinating castor oil seeds has been examined. Increasing the PEG concentration in the FBPasec reaction mixture elicited a progressive 3-fold decrease in the enzyme's K~ for fructose-l,6-P 2. The presence of PEG also: (i) increased the extent of FBPase c inhibition by high levels of fructose-l,6-Pz, (ii) enhanced the intensity of the enzyme's fluorescence emission spectra, and (iii) prevents dissociation of the active tetrameric native enzyme into inactive lower Mr forms during gel filtration HPLC. It is concluded that the activity and structure of plant FBPase c is modified by extreme dilution, probably as a result of partial deaggregation of the native tetrameric enzyme.

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Phosphate-Transferring Enzymes

Cited by 29 publications

References 0 publications

Stochastic kinetics of ribosomes: Single motor properties and collective behavior

Stochastic kinetics of ribosomes: Single motor properties and collective behavior

Studies with Lysine N6-Hydroxylase. Effect of a Mutation in the Assumed FAD Binding Site on Coenzyme Affinities and on Lysine Hydroxylating Activity

Effect of polyethylene glycol on the activity, intrinsic fluorescence, and oligomeric structure of castor seed cytosolic fructose‐1, 6‐bisphosphatase

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