<prompt> Guanidine special group is presesnt inArginineProlineTryptophanTyrosine  <response>: AMINO ACID SPECIAL GROUP Arginine Guanidinium Proline Pyrolidine Tryptophan Indole Phenylalanine Benzene Tyrosine Phenol Histidine Imidazole Methionine Thioether linkage Reference: Harpers illustrated biochemistry 30th edition 