Пурин

Химические свойства

very slightly yellow to cream crystalline powder

Использование

Organic synthesis, metabolism, and biochemi- cal research. (2) One of a number of basic compounds found in living matter and having a purine-type molecular structure.

Определение

ChEBI: The 9H-tautomer of purine.

Биосинтез

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.

Общее описание

Purine is a heterocyclic organic compound constituting a pyrimidine ring fused to an imidazole ring.

Методы очистки

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.]