BIOMOLECULES AND ENZYMES

Detailed explanation-1: -There are three amino acids that have basic side chains at neutral pH. These are arginine (Arg), lysine (Lys), and histidine (His). Their side chains contain nitrogen and resemble ammonia, which is a base. Their pKa’s are high enough that they tend to bind protons, gaining a positive charge in the process.

Detailed explanation-2: -At pH 7 lysine has a net charge of very close to +1. The carboxylic acid group is fully deprotonated (-1 charge). The alpha amino group is about 99% protonated (+1 charge). The side chain amino group is fully protonated (+1 charge).

Detailed explanation-3: -Lysine is an essential amino acid that has a net positive charge at physiological pH values making it one of the three basic (with respect to charge) amino acids.

Detailed explanation-4: -This is because they have a full charge on their side chain group at the normal physiological pH. Lysine and arginine are basic amino acids because their side chain group contains a full positive charge at the physiological pH.

Detailed explanation-5: -The pKa values of different groups present in Lysine are shown below. Hence overall charge at pH = 2, +1+1+0 = +2.