Adenosine monophosphate (AMPH) is a nucleotide that is present as a monomer in DNA and RNA. It consists of a phosphate group, a ribose molecule and an adenine molecule. Consequently, it can be found in three different ionic forms in aqueous solution (AMPH₃²⁺, AMPH₂⁺ and AMP−) plus its neutral form AMPH depending on the solution pH. The pKa of its double-protonated ion (z = +2) is 0.9, for its single-protonated form (z = +1) is 3.8 and for the deprotonated form (z = −1) is 6.1. Calculate the isoelectric point of AMPH and the pH value at which the fraction of AMPH₂⁺ reaches a maximum.