Models132 Models visible to you, out of a total of 232
The fitted function describes the pH-drop during 'forward'-shift experiments and the increase of the pH during 'reverse'-shift experiments. The estimated parameters are used to compute the changing pH level in the models of the pH.induced metabolic shift in continuous cultures under phosphate limitation of C. acetobutylicum. Furthermore, the parameters can be applied to join different independent experiments into a single data set.
To fit the changing pH level, an exponential function and a
3D structure prediction of LDH enzymes from four LAB by comparative modeling against x-ray structure of LDH from B. stearothermophilis (template, PDB ID: 1LDN). The computation was performed with a protocol that uses "automodel.very_fast" settings of Modeller program (http://salilab.org/modeller/).
Comparison of electrostatic potentials within the allosteric binding sites of LDH enzymes to estimate the binding affinity of the FBP molecule is performed with the PIPSA program. The program uses the structure of enzymes in the PDB format and computed electrostatic potentials in the GRD format.
Binding energies of phosphate ions to the allosteric and catalytic sites were estimated with a program GRID (http://www.moldiscovery.com/soft_grid.php). The calculations were performed for the modeled LDH structures from four LABs, at pH 6 and 7, in presence and absence of the FBP molecule. The phosphate ion was presented as a probe.
In order to estimate whether Pi has an activatory or an inhibitory effect on the enzymes, the computed probe binding energies (from GRID results, Part 4) were compared with those for the LDH from L. plantarum whose activity is known to be unaffected by Pi.
The binding energies of the Pi probe in the allosteric binding site (AS) and the COO probe in the catalytic binding site (CS) of LDH from L. plantarum were defined as E¬AS,threshold and ECS,threshold, respectively. For the other LDH enzymes,
Here, we use hyperbolic tangents to fit experimental data of AB fermentation in C. acetobutylicum in continous culture at steady state for different external pHs. The estimated parameters are used to define acidogenic and solventogenic phase. Furthermore, an transition phase is identified which cannot be assigned to acidogenesis or solventogenesis.
Several plots compare the fits to the experimental data.
Structural models of the LAB PYKs of L. lactis, L. plantarum, S. pyogenes and E. faecalis including the "best" docking solutions of potential allosteric ligands. The structures were derived by homology modeling based on the template of E. coli and B. stearothermophilus.
PYK models and ligands are provided as .pdb files and can be displayed by using the program PyMOL, for instance.