# Why is arginine's positive side chain classified as basic and not acidic?

Arginine has a positive side chain.

Doesn't this mean it wants to lose a proton H+? Isn't something that wants to lose or donate a proton an acid?

Yet my book states, "arginine has a positively charged side chain, i.e it is basic" .

• Protonated arginine sidechain makes a weak acid. May 25 '21 at 5:21