Isoelectric point calculations are critical in your biochemistry course and MCAT prep. The isoelectric point or pI gives you the pH at which the molecule has a net zero charge. This comes from a balance of protonation and deprotonation so that all positive and negative charges cancel out.
This video shows you how to calculate amino acid isoelectric point along with a shortcut to help you figure out WHICH pKa to use when given a side chain pKa value.
(Watch on YouTube: Isoelectric Point of Amino Acids. Click cc on the bottom right for video transcript)