New fluorescent hydrazide reagents for the oxidized 3'-terminus of RNA

The synthesis and properties of four new fluorescent reagents capable of forming moderately stable links to the 3' oxidized end of RNA are reported. All are hydrazide derivatives: pyrene butyric acid hydrazide, proflavine monosemicarbazide, proflavine monosuccinic acid hydrazide, and anthracene-9-carboxaldehyde carbohydrazone. In addition, procedures are given for coupling the bifunctional reagent carbohydrazide to the 3' end of RNA. These carbohydrazide adducts can easily be coupled in turn to a wide variety of fluorescent reagents having specificity for aliphatic amino groups, including isothiocyanates and sulfonyl halides. Thus a route exists for the preparation of an enormous variety of 3' fluorescent labeled RNAs. The carbohyrazide adducts are also useful for other synthetic procedures such as preparation of covalent tRNA dimers.