Purine degradation

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1. welcome

2. Biosynthesis and degradation of purine M.sridevi M.Sc. microbiology

3. Introduction Purine is a heterocyclic aromatic organic compound that consists of a pyrimidine ring fused to an imidazole ring. Purine is water soluble. Purine are found in high concentration in meat & meat products , especially internal organ such as liver & kidney .

4. Properties Purine is both a very weak acid and even weaker base. There are many naturally occurring purine . They include the nucleobases adenine Guanine Other notable purines are hypoxanthine , xanthine, Theo bromine , caffeine , uric acid , isoguanine .

5. purine metabolism Purine metabolism refer to the metabolic pathway to synthesize & breakdown purine that are present in many organism . Purine are biologically synthesized as nucleotides. Both adenine and guanine are derived from the nucleotide inosine monophosphate (IMP) or inosinic acid

6. The synthesis of IMP

7. Cont…

8. Synthesis of AMP and GMP from IMP For the synthesis of GMP , IMP undergoes NAD + dependent dehydrogenation to form xanthosine monophosphate (XMP) . Glutamine then transfer amide nitrogen to XMP to produce GMP. Aspartate condenses with IMP in the presence GTP to produce adenylsuccinate which , on cleavage , forms AMP .

9. Degradation of purine nucleotide The end product of purine metabolism in human is uric acid . Uric acid can serve as an important antioxidant . The normal concentration of uric acid in the serum of adults is in the range of 3 -7 mg/dl

10. Cont ….

11. Disorder of purine metabolism Gout is a genetic disorder of purine catabolism. It is caused by excessive formation of uric acid due to increased purine biosynthesis . Two characteristic features in gout are , Hyperuricemia Uricosuria

12. Gout Characterized by hyperuricemia and acute arthritic joint inflammation by deposition of uric acid crystals Primary gout is genetic and mainly affects men over 30 Secondary gout is associated with leukemia, polycythemia, HGPRT deficiency, renal insufficiency, lifestyle (rich foods)

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