Theme XVIII: Heterocycles
Purine: Structure and biological significance. Main purine bases: adenine, guanine and uric acid. Formulas, structures, tautomeric forms, derivatives.
Is called purine to the condensed nucleus pyrimidine-imidazole and is widely distributed in nature.
Purine is tautomeric and its derivatives may be from any of its two forms. Its nitrogen atoms confer basicity.
Among its derivatives are uric acid and urea, the ending product of the nitrogenous metabolism of many animals; caffeine, theobromine and theophylline; alkaloids of coffee, cocoa and tea.
Other derivatives such as adenine and guanine are forming structures of nucleic acids.
The mono, di and adenosine triphosphate (AMP, ADP and ATP) are nucleotides involved as coenzymes in numerous metabolic phosphorylations, playing a key role as conveyors of chemical energy in plants and animals.