purinbasen

Purine bases are nitrogen-containing heterocyclic compounds that form the core structural components of nucleic acids and several important biomolecules. The two primary purine bases in DNA and RNA are adenine and guanine. Additional purine derivatives, such as hypoxanthine and xanthine, appear as intermediates in purine metabolism and nucleotide turnover.

Chemically, purine bases consist of a fused imidazole and pyrimidine ring system, yielding a planar, highly conjugated structure. In biological systems, these bases attach to a sugar molecule to form nucleosides (adenosine, guanosine, etc.) and further to phosphate groups to make nucleotides (AMP, GMP, etc.). The purine-nucleotide pool participates in genetic information storage, transmission, and a wide range of biochemical processes.

Biological roles of purine bases include their function in nucleic acids, where adenine pairs with thymine (or uracil in RNA) and guanine pairs with cytosine, via hydrogen bonds. Purine nucleotides such as ATP and GTP serve as universal energy carriers and participate in signaling and metabolic regulation. Purine-derived cofactors and coenzymes—such as NAD+, FAD, and coenzyme A derivatives—contain purine bases and are essential for redox reactions and metabolism.

Biosynthesis and salvage pathways maintain the cellular purine pool. Purines are produced de novo from simple precursors, and free purine bases or nucleosides are recycled through salvage pathways. Degradation ultimately yields uric acid in humans, which is excreted in urine. In many mammals, additional enzymes degrade uric acid further, but humans lack urate oxidase, contributing to variability in uric acid levels.

Purine bases are universal to life, underpinning genetic material, energy metabolism, and a range of enzymatic cofactors. Abnormal purine metabolism can contribute to diseases such as gout and other metabolic disorders.