Question

At a pH above its pKa(side chain), the epsilon-amino group of lysine is ___.

a) Protonated
b) Deprotonated
c) Neutral
d) Hydroxylated

Answer 1

At a pH above its pKa(side chain), the epsilon-amino group of lysine is deprotonated.

Step-by-step explanation:

At a pH above its pKa(side chain), the epsilon-amino group of lysine is deprotonated.

In its side chain, lysine has an epsilon-amino group (-NH2) that is basic. When the pH is above the pKa of the side chain, the epsilon-amino group will lose a proton and become negatively charged, resulting in deprotonation.

For example, at a pH of 7.4, which is higher than the pKa of lysine's side chain, the epsilon-amino group will be deprotonated and exist as -NH3+