April 25, DNA Day


‘We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.).

This structure has novel features which are of considerable biological interest.”…

John Watson and Francis Crick in Molecular Structure of Nucleic Acids. A structure for deoxyribose nucleic acid.

Nature No. 4356, April 25, 1953


DNA Day also marks the completion of the Human Genome Project, the 13-year international effort that identified the order, or sequence, of more than 3 billion bases in human DNA. The Human Genome Project was finished in 2003, 50 years after Watson and Crick described DNA as a double helix. (Source: National  Library of Medicine)




I would like to invite you to see two presentations courtesy of the National Genome Research Institute, that, at different levels, present different aspects of Genetics research (the pictures are from the U.S. Department of Energy Genome Program’s Genome Management Information System -GMIS):

1.- How Proteins Are Made



2.- Single Nucleotide Polimorphism:

Making SNPs Make Sense


Additional interesting presentations can be found at:

Online Education Kit: Understanding the Human Genome Project



                                                                                       HAPPY DNA DAY!!!



Allopurinol and Gout

Original Question


Answer  to NcM-01: (a)


During the catabolism of purine bases Xanthine Oxidase catalyzes the conversion of Hypoxanthine to Xanthine and the conversion of Xanthine to uric acid.




                                                         Xanthine —> Uric Acid



Allopurinol is a structural analog of Hipoxanthine:


                                            Hipoxanthine structure




                                                   Allopurinol structure




Allopurinol can bind to Xanthine Oxidase and be converted to alloxanthine (oxypurinol), the metabolite responsible of most of the inhibitory effects of the administration of allopurinol.


 “ The action of oral allopurinol differs from that of uricosuric agents, which lower the serum uric acid level by increasing urinary excretion of uric acid. Allopurinol reduces both the serum and urinary uric acid levels by inhibiting the formation of uric acid. The use of allopurinol to block the formation of urates avoids the hazard of increased renal excretion of uric acid posed by uricosuric drugs. (Source: U.S. Food and Drug Administration Center for Drug Evaluation and Research. FDA Oncology Tools Product Label Details for Prescribing allopurinol)


The solubility of Xanthine and Hypoxanthine is higher than the solubility of Uric acid and the renal clearance is at least 10 times higher than the clearance for uric acid.


For more information about Allopurinol and Gout, follow these links:


Francis, M.L. et al: Gout


 Manual Merck: Gout



If you already studied Pharmacology, try to answer the following questions


Is it indicated to use Allopurinol during an accute attack of Gout?


Which other uses does Allopurinol have in Medicine?