Correlation Between Reduced Mass and Gibbs Energy Change of Reaction

<p>The correlation between the Gibbs free energy change of reaction and the reduced mass was clarified. In the case of bond formation reactions, the computed Gibbs energy change of reaction increased in the positive direction as the reduced mass increased. In the case of dissociation equilibrium reactions, such as the dissociation of tetrahedral carbonyl addition compound, the computed Gibbs energy change of reaction also increased in the positive direction as the reducing mass increased, but the extent of the change was smaller than in the case of bond formation reactions. The results were in good agreement with those derived from the relationship between yield and reduced mass, indicating that was originated from the correlation between the Gibbs energy change and the reduced mass.</p>

Correlation Between Reduced Mass and Gibbs Energy Change of Reaction

<p>The correlation between the Gibbs free energy change of reaction and the reduced mass was clarified. In the case of bond formation reactions, the computed Gibbs energy change of reaction increased in the positive direction as the reduced mass increased. In the case of dissociation equilibrium reactions, such as the dissociation of tetrahedral carbonyl addition compound, the computed Gibbs energy change of reaction also increased in the positive direction as the reducing mass increased, but the extent of the change was smaller than in the case of bond formation reactions. The results were in good agreement with those derived from the relationship between yield and reduced mass, indicating that was originated from the correlation between the Gibbs energy change and the reduced mass.</p>

Optimal Duration of the Preincubation Phase in Enzyme Inhibition Experiments

This report describes an algebraic formula to calculate the optimal duration of the pre-incubation phase in enzyme-inhibition experiments, based on the assumed range of expected values for the dissociation equilibrium constant of the enzyme–inhibitor complex and for the bimolecular association rate constant. Three typical experimental scenarios are treated, namely, (1) single-point primary screening at relatively high inhibitor concentrations; (2) dose-response secondary screening of relatively weakly bound inhibitors; (3) dose-response screening of tightly-bound inhibitors.

Optimal Duration of the Preincubation Phase in Enzyme Inhibition Experiments

This report describes an algebraic formula to calculate the optimal duration of the pre-incubation phase in enzyme-inhibition experiments, based on the assumed range of expected values for the dissociation equilibrium constant of the enzyme–inhibitor complex and for the bimolecular association rate constant. Three typical experimental scenarios are treated, namely, (1) single-point primary screening at relatively high inhibitor concentrations; (2) dose-response secondary screening of relatively weakly bound inhibitors; (3) dose-response screening of tightly-bound inhibitors.

Potassium Glutamate and Glycine Betaine Induce Self-Assembly of Sliding Clamps into Higher Order Oligomers

ABSTRACTSliding clamps are oligomeric ring-shaped proteins that increase the efficiency of DNA replication. The stability of the Escherichia coli β-clamp, a homodimer, is particularly remarkable. The dissociation equilibrium constant of β is of the order of 10 pM in buffers of moderate ionic strength. Coulombic electrostatic interactions have been shown to contribute to this remarkable stability. Increasing NaCl concentration in the assay buffer results in decreased dimer stability and faster subunit dissociation kinetics in a way consistent with simple charge-screening models. Here, we examine non-Coulombic ionic effects on the oligomerization properties of sliding clamps. Replacing NaCl by KGlu, the primary cytoplasmic salt in E. coli, results in the formation of assemblies that involve two or more rings stacked face-to-face. Results can be quantitatively explained on the basis of unfavorable interactions between KGlu and the functional groups on the protein surface, which drive biomolecular processes that bury exposed surface. Similar results were obtained with the S. cerevisiae PCNA sliding clamp, suggesting that KGlu effects are not specific to β. Clamp association is also promoted by glycine betaine, a zwitterionic compound that accumulates intracellularly when E. coli is exposed to high concentrations of extracellular solute. Possible biological implications are discussed.

Synthesis and Characterization of Cry2Ab–AVM Bioconjugate: Enhanced Affinity to Binding Proteins and Insecticidal Activity

Bacillus thuringiensis insecticidal proteins (Bt toxins) have been widely used in crops for agricultural pest management and to reduce the use of chemical insecticides. Here, we have engineered Bt toxin Cry2Ab30 and bioconjugated it with 4”-O-succinyl avermectin (AVM) to synthesize Cry2Ab–AVM bioconjugate. It was found that Cry2Ab–AVM showed higher insecticidal activity against Plutella xylostella, up to 154.4 times compared to Cry2Ab30. The binding results showed that Cry2Ab–AVM binds to the cadherin-like binding protein fragments, the 10th and 11th cadherin repeat domains in the P. xylostella cadherin (PxCR10–11), with a much higher affinity (dissociation equilibrium constant KD = 3.44 nM) than Cry2Ab30 (KD = 28.7 nM). Molecular docking suggested that the macrolide lactone group of Cry2Ab–AVM ligand docking into the PxCR10–11 is a potential mechanism to enhance the binding affinity of Cry2Ab–AVM to PxCR10–11. These findings offer scope for the engineering of Bt toxins by bioconjugation for improved pest management.