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 a Q regarding PRPP  




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  #1

ribose-5-p converts to PRPP by PRPP synthase

PRPP used for making-de nevo- purine and prymidines

defect in PRPP synthase is one of causes of gout(hyperuicemia)(a UW q) b/c of lack of inhibitory action of IMP,AMP,GMP ,,,also PRPP is needed for purine salvage

but my question is ,when we have defect in PRPP synthase so we should not have PRPP so how purines are made at first place to cause problem later?

please anyone ?




  #2

Hey,

You probably no longer need this answer, but I was curious and looked into this.

So, I think your right. A defective PRPP synthetase which resulted in a non-functioning enzyme most likely would not be compatible with life. I believe the the referred scenario, in which a PRPP synthetase defect results in gout, is most likely caused by a mutation that increases the activity of the enzyme.

This website has a table about half way down the page that indicates this:
themedicalbiochemistrypage....nucleotide-metabolism.html

My med school biochem notes also refer to mutations in the enzyme that result in mis-regulation of PRPP Synthetase which results in failure to decrease the enzymes activity (via Feedback inhibition) in the presence of excess purines.

So, most likely a mutation on the enzyme in an allosteric binding site for purines.







  #3

Hi guys

first of all I want to tell you that AMP,IMP,IMP all inhibit PRPP AMIDOTRANSFERASE not PRPP Synthetase.

PRPP AMIDOTRANSFERASE is the rate limiting enzyme in de novo synthesis of Purines.

Any additional info is very welcome.grin


  #4

Hi....

purines and pyrimidines may come from nucleic acids of dying and degenerating cells.


  #5

Hi.

purines and pyrimidines can come from the nucleic acids of the dying and degenerating cells.





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