Te amino acid arginine ionizes according to the following scheme:

(a) Calculate the isoelectric point of arginine. You can neglect contributions from form I. Why?
(b) Calculate the average charge on arginine when pH - 9.20.
(c) Is the value of average charge you calculated in part b reasonable, given the pI you calculated in part a? Explain your answer.

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NH2 NH2 C= N-H NH (CH2)3 NH2 NH2 pKa 2.17 H pKa 12.5 NH H K 8.99 NH (CH23 H-NT-C- COOH NH H (CH2)3 (CH2)3 +H H-N-C-COO H2N-C- COO IV