Question 8

(Multiple Choice)

Lysine contains two amine groups (pKa values of 9.0 and 10.0)and a carboxylic acid group (pKa 2.2).In a solution of pH 9.5,which of the following would best describe the protonation and charge state of lysine?


A)carboxylic acid: deprotonated and neutral;both amines: protonated and positive
B)carboxylic acid: deprotonated and negative;both amines: deprotonated and neutral
C)carboxylic acid: deprotonated and negative;amine (pKa 9.0): deprotonated and neutral;amine (pKa 10.0): protonated and positive
D)carboxylic acid: deprotonated and negative;amine (pKa 9.0): protonated and positive;amine (pKa 10.0): deprotonated and neutral
E)carboxylic acid: deprotonated and neutral;amine (pKa 9.0): deprotonated and neutral;amine (pKa 10.0): protonated and positive

Answer