Compute the iso-electric point of a protein. I understand that you want to substitute variations of pH until you find out a pI which is close to zero. What I want is a detailed illustration of the process for a simple protein (say four amino acids, preferably charged). It would be helpful if you could as well give a similar protein and answer only so I can check my understanding. It would as well be helpful if you could declare any constants (that is, pH = 5) in advance of both problems.