<prompt> Salvage pathway of purine nucleotide synthesis are used by all except ?BrainLiverRBCLeukocytes  <response>: Purine nucleotide synthesis occurs by two pathways :- 1.De novo synthesis 2.Salvage pathway Liver is the major site of purine nucleotide biosynthesis de novo. Ceain tissues cannot synthesize purine nucleotides by de novo patyway, e g. brain, erythrocytes and polymorphonuclear leukocytes. These are dependent on salvage pathway for synthesis of purine nucleotides by using exogenous purines, which are formed by degradation of purine nucleotides synthesized in liver. 