CpH

CpH is an acronym used in several disciplines, and its exact meaning depends on the context. In computational chemistry and biophysics, CpH most often stands for constant pH, as in CpHMD (constant-pH molecular dynamics). In this approach, the protonation states of ionizable groups in a biomolecule are allowed to fluctuate during molecular dynamics simulations in response to the surrounding pH. Variants include discrete-state and continuous-titration-coordinate formulations. CpHMD enables estimation of pKa values, pH-dependent structural changes, and the effect of protonation on binding and catalysis. Typical outputs include protonation-state populations and pH-dependent free-energy profiles.

In acid-base and protein chemistry, CpH is sometimes used to denote the critical pH, the pH at which a species undergoes a qualitative change in protonation state or charge, affecting properties such as solubility, crystallization, or activity. Practically, CpH is linked to pKa values via titration curves and Henderson-Hasselbalch relationships; it is determined experimentally by titration or computationally from pKa predictions.

Because CpH is not a standardized term, it is essential to consult the source for its precise meaning. Related concepts include pKa, acid-base titration, and the methods for estimating pH-dependent behavior in macromolecules, including CpHMD.