Purine 98%

There are two pathways for the synthesis of purine nucleotides in the pharmaceutical grade, one is the de novo synthesis pathway, one is the salvage synthesis pathway, and the de novo pathway is the main pathway.

De novo synthesis of 1 purine nucleotides

Liver is the main organ of the synthesis of purine nucleotides in vivo, and the second is the small intestine mucosa and thymus. Purine nucleotide synthesis site in the cytosol, the synthesis of raw materials including phosphate, aspartate, glycine, glutamine, one carbon unit and CO2, etc.. The primary reaction step is divided into two stages: first of all synthesis of inosine monophosphate (IMP) and imp changed back into adenine nucleotide (AMP) and guanine nucleotides (GMP). The source of each element of the purine ring is as follows: N1 provided by ASP, C2 provided by N10- FH4, C8 by N5, N10-, FH4,, N3, N9 provided by glutamine, C4, C5, N7 provided by glycine, C6 provided by CO2. The de novo synthesis of purine nucleotides is characterized by the gradual synthesis of purine nucleotides on the basis of the molecular basis of the phosphoric acid, which is not the first synthesis of purine bases and then combined with the. The key enzymes in the process include PRPP amide transfer enzyme, PRPP synthetase. PRPP amidotransferase is an allosteric enzyme, the monomer activity of two dimers form no activity. In IMP, AMP and GMP, the active form is transformed into an inactive form, while PRPP is the opposite. De novo synthesis regulation mechanism is feedback regulation, mainly in the following several parts: synthesis of purine nucleotide initial stage of PRPP synthetase and PRPP amide transfer enzyme activity can be inhibited by the synthetic products imp, AMP and GMP; in the formation of AMP and GMP process, generated an excess of amp Control amp, GMP synthesis, an excess of GMP GMP control the generation, does not affect the amp synthesis; change the imp into amp requires GTP, and the imp into GMP requires ATP.

2 purine nucleotide salvage synthesis

The main enzyme reaction including adenine phosphoribosyl transferase (aprt), hypoxanthine guanine phosphoribosyl transfer enzyme (HGPRT). Purine nucleotide salvage synthesis of physiological significance: energy and amino acid consumption saving the time of de novo synthesis; in some tissues and organs, such as the brain, bone marrow due to the lack of the enzyme system of de novo synthesis of purine nucleotides, and only purine nucleotide salvage synthesis.

3 the interaction of purine nucleotides

IMP can be transformed into AMP and GMP, AMP and GMP can also be transformed into IMP. The mutual transformation between AMP and GMP.

4 generation of DNA

In vivo DNA is formed by the reduction of the corresponding RNA at the level of two phosphoric acid. This reaction is catalyzed by the.

5 purine nucleotides

Purine analogues: 6- (6MP), 6-, 8-, N, guanine, guanine, guanine, guanine, guanine, guanine, guanine. 6MP is widely used, similar to the structure and hypoxanthine, in vivo phosphorylated ribose generated 6MP nucleotides, and in the form of the inhibition of IMP change response to AMP and GMP.

Amino acid analogues: n, N, N, -5-, 6-, N, N, N, N, N, N, N, N, n. The structure is similar to that of glutamine, which can interfere with the function of glutamine in the synthesis of purine nucleotides, thus inhibiting the synthesis of purine nucleotides.

The folic acid analogues: aminopterin and methotrexate (MTX) are analogues of folic acid, competitive inhibition of dihydrofolate reductase, folate is not returned to dihydrofolate and tetrahydrofolate, thereby inhibiting the synthesis of purine nucleotides.