Chemical Properties
very slightly yellow to cream crystalline powder
Definition
A simple nitrogenous organic molecule with a double ring
structure. Members of the purine group include adenine and guanine, which are constituents of the nucleic acids, and certain
plant alkaloids, such as caffeine and theobromine.
Definition
ChEBI: The 9H-tautomer of purine.
Definition
purine: An organic nitrogenous base(see formula), sparingly soluble inwater, that gives rise to a group ofbiologically important derivatives,notably adenine and guanine,which occur in nucleotides and nucleicacids (DNA and RNA).
Biosynthesis
Basically, the same pathway is found in all organisms capable of purine biosynthesis de novo. The initial substrate is the highly phosphorylated sugar 5-phosphoribosyl-α-1-pyrophosphate (PRPP). An amino group is transferred from glutamine to PRPP catalyzed by the enzyme glutamine PRPP amidotransferase. After that, it takes four reactions to complete the imidazole ring and an additional five reactions to synthesize the pyrimidine moiety and thereby to complete the purine molecule. In some bacteria (e.g., B. subtilis and Escherichia coli), the third step is also catalyzed by a second enzyme (purT) that uses formate instead of a tetrahydrofolic acid derivative as formyl donor. The sixth step has been found to be a two-step reaction, which in some organisms is catalyzed by a single enzyme. The end product of the de novo purine biosynthetic pathway is IMP. After the formation of IMP, purine synthesis splits into two separate pathways leading to the synthesis of AMP and GMP. The control point for feedback inhibition by purine nucleotides and activation by PRPP is on the activity of the first enzyme of the pathway glutamine PRPP amidotransferase. The branching from IMP is regulated by ATP and GTP to ensure a proper balance between ATP and GTP.
General Description
Purine is a heterocyclic organic compound constituting a pyrimidine ring fused to an imidazole ring.
Purification Methods
It crystallises from toluene or EtOH, and sublimes at 100-150o/0.1mm or 160o/10-4mm. The picrate has m 207-209o after crystallisation from 20volumes of H2O. [Beilstein 26 H 354, 26 III/IV 1736.]
