Modification with adipic dihydrazide

In the particular case of polysaccharides, this reaction has been used for the modification of several types of biopolymers with different applications [28, 29]. As an example, a monoaldehyde derivative of P CD (2) was prepared from the hydrolysis of product 1 and then grafted, by a reductive amination-type reaction, onto an alginate derivative selectively modified with adipic dihydrazide (alg-ADH) (Scheme 7.5). The new polymeric materials obtained, alg-ADH intermediate and jS-CD-grafted alginate were fully characterized in terms of chemical integrity and purity by high-resolution NMR spectroscopy [30]. 

Figure 1.112 Phosphate groups can be modified with adipic acid dihydrazide in the presence of a carbodi-imide to produce hydrazide derivatives. This is a common modification route for the 5 -phosphate group of oligonucleotides.

Most proteins contain an abundance of carboxylic acid groups from C-terminal functionalities and aspartic and glutamic acid side chains. These groups are readily modified with bis-hydrazide compounds to yield useful hydrazide-activated derivatives. Both carbohydrazide and adipic acid dihydrazide have been employed in forming these modifications using the carbodi-imide reaction (Wilchek and Bayer, 1987). 

The following protocol describes the modification of DNA or RNA probes at their 5 -phosphate ends with a bis-hydrazide compound, such as adipic acid dihydrazide or carbohydrazide. A similar procedure for coupling the diamine compound cystamine can be found in Section 2.2 (this chapter). 

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