Nonradioactive primary labels

Fig. 7.2. Modified nucleotides to which primary labels can be attached (I—III) and nonradioactive primary labels (IV—VIII), Photohaptens (IX) are readily attached to nucleic acids. Particularly popular are DIG-11-dUTP (VI) and fluorescein-12-dUTP. Bases 1—III contain both a linker and a reactive amino group. Usually an extra linker is included to improve further accessibility (e.g., VI and VIII). Although linkers are a necessity for biotin, they are not absolutely required for the detection by labeled antibody (BrdU (IV), AAF (VID). Similarly, trinitrophenyl-glutathione (TNP-GSH) readily reacts with mercuricytosine (V) and the TNP can be detected using specific antibody. R2 in VII can be either an H (AAF) or an I (AAIF).

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