Salvage synthesis refers to the reuse of parts of nucleotides in resynthesizing new nucleotides. Salvage synthesis requires both breakdown and synthesis reactions in order to exchange the useful parts.

Important enzymes in the salvage synthesis of nucleotides (Figure 22.2) are as follows:

1. Phosphoribosyl transferases, which interconvert free bases plus PRPP with nucleoside monophosphates;

2. Nucleotidases, which cleave phosphates from nucleoside monophosphates to form free nucleosides;

3. Nucleoside kinases, which phosphorylate nucleosides to nucleoside monophosphates (see here);

4. Phosphorylases (see Figure 22.2), which use phosphate to separate the base from ribose, forming free bases and ribose-1-phosphate.

5. Phosphodiesterases, which convert oligonucleotides to nucleoside monophosphates;

6. Endonucleases, which convert nucleic acids to oligonucleotides (see Figure 22.2)