Please be sure to explain how to arrive at the answer The compound 5\' adenosine
ID: 1023691 • Letter: P
Question
Please be sure to explain how to arrive at the answer
The compound 5' adenosine monophosphate (5' AMP) is shown below. The hydroxyl that is part of the phosphoryl group and labeled "1" has a pK_a of 0.9; the hydroxyl that is part of the phosphoryl group and labeled "2" has a pK_a of 6.1; and the protonated N1 of the adenine moiety has a pK_a of 3.8. Given this information, what will be the average, net charge of 5' AMP when the pH equals 6.1? To simplify matters, assume that if the pH is 2 or more units from the pK_a of a particular group, then that group is completely protonated or unprotonated, as the case might be. +1.25 +1.75 0 +1.5 -0.5 -1 +0.75 -1.5 -0.25 +1 -1.25 +0.25 +2 -2 +0.5 -0.75 -1.75Explanation / Answer
pka for 1 is 0.9 so at ph = 6.1 , it is deprotonated and therefore has a charge = -1
and
pka for 2 is 6.1 so at ph = 6.1 , it is not deprotonated and therefore charge = 0.0
and
pka for 3 is 3.8 so at ph = 6.1 , it is deprotonated and therefore has a charge = 0.0
therefore
the total charge = -1 + 0.0 + 0.0
= -1
the correct answer is -1.