A. The nucleotide loop is boxed. B. Purines and purine analogues found in Cbas: [1], purine; [2]. hypoxanthine; [3], adenine; [4], 2-methyladenine; [5], 2-methylmercaptoadenine; [6], 2-methylsulfinyladenine; [7], 2-methylsulfonyladenine; [8], guanine. C. Benzimidazole and its analogues: [1], benzimidazole; [2], 5-methylbenzimidazole; [3], 5,6-dimethylbenzimidazole; [4], 5-hydroxybenzimidazole; [5], 5-methoxybenzimidazole; [6], 5-methoxy-6-methylbenzimidazole; [7], naphthimidazole. D. Phenolics: [1], phenol; [2], p-cresol.