The correct answer is (d) pH
The explanation: Partition coefficient may be defined as,
\(P=\frac{C_t}{C_b}\) where Ct and Cb represent the concentrations in the top and bottom phases respectively. The partition coefficient is exponentially related to each of the following:
* Surface area.
* Surface charge of the particles.
* Difference in the electrical potential.
* hydrophobicity of the phases.
The influence of pH on protein partition is complex. A given protein distributes differently between the phases at different pH’s and ionic strength. But the presence of phosphate ions affects the partition coefficient in such way that the ions distribute themselves unequally resulting in electrostatic potential (and pH) differences. This means that systems may be ‘tuned’ to enrich an enzyme in one phase, ideally the upper phase with cell debris and unwanted enzymes in the lower phase.