At Physiological PH, the Ionized State of the Amino (NH₂)

Question

At physiological pH, the ionized state of the amino (NH2) group in the R group of lysine is: A)NH2. B)NH3⁺. C)NH4⁺⁺. D)NH^-.

Accepted Answer

At physiological pH (around 7.4), the amino group in the side chain of lysine is protonated, giving it a positive charge, which corresponds to choice B.