Salvage Pathway : Purine Salvage Pathway

Salvage Pathway : Purine Salvage Pathway

    

Purine nucleotides can be synthesized in two distinct pathways. First, purines are synthesized de novo, beginning with simple starting materials such as amino acids and bicarbonate. Unlike the bases of pyrimidines the purine bases are assembled already attached to the ribose ring. Alternatively, purine bases released by the hydrolytic degradation of nucleic acid and nucleotides, can be salvaged and recycled. Purine salvage pathway's are especially noted for the energy that they save and the remarkable effects of their absence.

Salvage pathway utilizes the bases derived from turn over of the cellular nucleic acid or obtained from the dietary nucleic acid. The bases are not degraded but can be re- -converted into purine nucleotide. The bases as added to ribose sugar and phosphate in 2- the form of 5-phosphoribosyl -1-pyrophosphate. (PRPP) and reforms the purine nucleotide. This is referred to as salvage. pathway.

Hypoxanthine + PRPP------*--------> IMP+  iPP

This reaction is catalyzed by * hypoxanthine guanine- -phosphoribosyl transferase (HGPRT) and pyrophosphate is released.

                                              Adenine + PRPP ---------*---------> AMP + iPP

This reaction is catalyzed by *adenine-phosphoribosyl transferase (APRT) and *pyrophosphate is released.

Guanine + PRPP --------*---------> GMP+ iPP

This reaction is catalyzed by *Hypoxanthine- guanine-phosphorybooyl transferase (HGPRT) and the pyrophosphate is released.