At the opposite side of the active site is a small hydrophobic pocket that accommodates the methyl substituent, with the thiol of Cys188 placed 4.16 Å from the Si face of the enediolate, ideally positioned for protonation that leads to the observed R-configured α-phenylpropionic acid (2, L=Ph & S=Me).
It was determined that protonation sites on the isomers can vary depending on the position of amino groups, and the resulting protonation sites play a role in the gas-phase stability of the isomer.
In either position of P4VP, electrode system becomes dependent on the pH sensitivity or the ratio of protonation on P4VP.
30 The positive shift in the position of the first reduction wave of 1 in the presence of TFA indicates that the protonation of the iron sulfur cluster core already occurs at low acid concentration, which interestingly is not the case for the less electron-rich Fe3S2 CO 9 parent system.
For oxalyl CoA decarboxylase, a structure of the enamine intermediate has been determined, and it has a water molecule in just such a position, poised for protonation of the enamine carbon (46).
Similar to S90C, S86F is a shift from a polar aa residue to a non-polar one in a suitable position to destabilize protonation of the Schiff base linkage between retinal and the opsin, leading to an unprotonated Schiff base, which is typical of UVS pigments [ 11].
We hypothesize that it is the dynamics of protonation, rather than protonation per se, that affects the activation status of the class-A GPCR.
The effects of protonation on the phase transitions of the azomethines are investigated.
Adjustment of protonation state was performed manually in Maestro.
Protonation will also affect base stacking and other interactions, however, so that effects of protonation will be sequence-dependent.
