Purine metabolism

METABOLISM OF PURINE NUCLEOTIDES

Origin of the ring atoms of purine

Purine bases are recycled from Salvage Path way

Adenine + PRPP AMP+ PPi

Guanine + PRPP GMP+Ppi

Hypoxanthine+ PRPP IMP+PPi

APRT

HGPRT

HGPRT

GOUT Primary Gout: Enzyme defect Secondary Gout 1.Over production of Uric acid (Cancer,

Starvation,alcohol) 2.Decreased excretion of uric acid (renal failure,

Lactic acidosis, alcohol)

GOUTSymptoms: Arthritis of Metatarsophalangeal jointPrecipatated by high purine diet & alcoholTophi – chronic cases Treatment:Decreased purine intake Allopurinol- xanthine oxidase inhibitorProbenacid – uricosuricsColchicine – anti inflammatory

LESCH- NYHAN SYNDROMEX – linked disorderHGPRTase deficiencySelf mutilation, mental retardation,

nephrolithiasis

PURINE NUCLEOTIDE ANALOGSUsed as Anti cancer agents:MercaptopurineMethotrexateAzaserine 6-TG (thioguanine)8 AG (Azaguanine)