We are generally dealing with 20 amino acid, but you people should know that there are two more amino acid viz Selenocysteine (21st) Pyrrolysine (22nd)
I want to add some info. In general, all amino acids are denoted with their three-letter symbol or their one-letter symbol. Selenocysteine : Sec / U Pyrrolysine : Pyl / O Also, their structures (radical groups) are : Selenocysteine : - CH2 - SeH Pyrrolysine : - CH2 - CH2 - CH2 - CH2 - NH - CO - 1-Pyrroline - CH3
