A3A specificity to ssDNA background and substrate. Fluorescence anisotropy of TAMRA-labeled ssDNA sequences binding to A3A(E72A). (a) Binding of A3A to poly nucleotide (12 mers): Poly A (blue), Poly T (red) and Poly C (green), (b) Binding to Poly A (blue), 5A-C-6A (red), 5A-U-6A (green), (c) Binding to Poly T (blue), 5T-C-6T (red), 5T-U-6T (green).