Isoelectric Point OF Amino Acid

At isoelectric point the amino acids have least /maximum solubility in water.

At the isoelectric point, amino acids are present as

Statement-I: Solubility of an amino acid is maximum at isoelectric point Statement-II: At isoelectric point amino acids exists as Zwitter ion.

What is isoelectric point amino acid ? How does it help in the sepration of amino acids ?