So let's continue our discussion on the isoelectric points of proteins. Previously we had example one and example two in which we actually determined what the isoelectric point of a protein was. Now let's look at example three. So in example three, we want to basically determine the net charge on this protein that consists of five amino acids at these four different pieces h value. So let's begin by actually drawing the structure of this protein. So let's begin with histidine.