The relative enthalpy of the optimized GSH conformers and the GSH/OH^• complexes.

<p>The reference conformer (red line) was the representative structure obtained from the molecular dynamics simulation of GSH without OH<b>^•</b>. The calculations were carried out at the BHandHLYP/6-31G(d) level of theory combined with the SMD implicit (continuum) solvent model.</p

The structures that contained the maximum (3) number of interactions between GSH and the OH^• based on the geometrical criteria are depicted (I. – zwitterionic group, II. – anionic group).

<p>The interactions based on geometrical criteria are indicated with blue, dashed lines, while those resulted from the AIM analyses are depicted with green points (bond critical points, BCPs).</p

The maximum values of the radial distribution functions (<i>g(r)</i>) between the oxygen atom of OH^• and all heavy atoms in GSH.

<p>The normalized values (Norm.) were calculated (Norm.  = <i>g(r)</i>max/min[<i>g(r)</i>max]) and are also tabulated.</p

Glutathione – Hydroxyl Radical Interaction: A Theoretical Study on Radical Recognition Process

<div><p>Non-reactive, comparative (2×1.2 μs) molecular dynamics simulations were carried out to characterize the interactions between glutathione (GSH, host molecule) and hydroxyl radical (OH^•, guest molecule). From this analysis, two distinct steps were identified in the recognition process of hydroxyl radical by glutathione: catching and steering, based on the interactions between the host-guest molecules. Over 78% of all interactions are related to the catching mechanism <i>via</i> complex formation between anionic carboxyl groups and the OH radical, hence both terminal residues of GSH serve as recognition sites. The glycine residue has an additional role in the recognition of OH radical, namely the steering. The flexibility of the Gly residue enables the formation of further interactions of other parts of glutathione (e.g. thiol, α- and β-carbons) with the lone electron pair of the hydroxyl radical. Moreover, quantum chemical calculations were carried out on selected GSH/OH^• complexes and on appropriate GSH conformers to describe the energy profile of the recognition process. The relative enthalpy and the free energy changes of the radical recognition of the strongest complexes varied from −42.4 to −27.8 kJ/mol and from −21.3 to 9.8 kJ/mol, respectively. These complexes, containing two or more intermolecular interactions, would be the starting configurations for the hydrogen atom migration to quench the hydroxyl radical <i>via</i> different reaction channels.</p></div

The radial distribution functions (<i>g(r)</i>) were calculated between the oxygen atom of water (blue curves) or OH^• (black curves) and all heavy atoms in GSH for the GSH/OH^• system.

<p>The maximum <i>g(r)</i> values and the corresponding distance for OH^• are indicated in the lower right corner of each graph.</p

The free energy surface of the GSH×××OH^• radical interaction determined by metadynamics calculation.

<p>The free energy surface of the GSH×××OH^• radical interaction determined by metadynamics calculation.</p

The volumetric map was created for the radical (OH^•) occurrence around those 838 structures where the OH^• interacts with at least two heavy atoms of the GSH.

<p>The volumetric map was created for the radical (OH^•) occurrence around those 838 structures where the OH^• interacts with at least two heavy atoms of the GSH.</p

The percentage distribution of the structures on the RMSD – R_gyr (upper panel) and HT – CYS-HT surfaces was calculated for the GSH and the GSH/OH^• systems (left panels).

<p>Representative structures from the most populated region from the RMSD – R_gyr surface are shown as well. The different origin of the representative structures is indicated by colored carbon atoms (green – GSH, brown – GSH/OH^•). The differences between surfaces were also calculated (right panel).</p

The average SDS content (x2) of the micelle (upper panel) and their relative shape anisotropy (lower panel, Κ2) as a function of the cluster size.

<p>The average SDS content (x2) of the micelle (upper panel) and their relative shape anisotropy (lower panel, Κ2) as a function of the cluster size.</p

Temperature dependent critical micelle concentration obtained by fluorimetric and tensiometric experiments (noted by cmc^ex_f(T) and cmc^ex_t(T), respectively), ideal critical micelle concentration (cmc^id), mole fraction of NaCA (<i>x₁</i>) in the mixed micelle and interaction parameter between the building units (β_1,2) as a function of temperature for the binary mixture of NaCA and SDS (1∶1).

<p><b>cmc_1,f (T)</b>- cmc of pure NaCA measured by fluorimetry.</p><p><b>cmc_2,</b>_{<b><i>f</i></b>}<i> </i><b><i>(T)</i></b>- cmc of pure SDS measured by fluorimetry.</p