2.2 SQUARE inside PROTEIN p0 inside PROTEIN p1 inside PROTEIN p2 inside SIMPLE_MOLECULE L_minus_Histidine inside SIMPLE_MOLECULE Carnosine inside SIMPLE_MOLECULE _space_1H_minus_Imidazole_minus_4_minus_ethanamine inside SIMPLE_MOLECULE _space_4_minus__space__beta__minus_Acetylaminoethyl_space_imidazole STATE_TRANSITION L_minus_Histidine _space_1H_minus_Imidazole_minus_4_minus_ethanamine c0 c2 STATE_TRANSITION _space_1H_minus_Imidazole_minus_4_minus_ethanamine _space_4_minus__space__beta__minus_Acetylaminoethyl_space_imidazole c2 c3 STATE_TRANSITION Carnosine L_minus_Histidine c1 c0