Now, when we are below the PTA value of 4.7, or actually, when we are below the PH value of 4.7, these are going to be protonated. Now, when this is protonated, we no longer call it aspartate. We call it aspartic acid. So aspartate refers to our amino acid form that exists in the physiological PH of around seven. So this, in its deprotonated form, is known as aspartate. But if we protonate this, then it's called aspartic acid.