Categories :

What are the disorders of purine metabolism?

What are the disorders of purine metabolism?

From a clinical point of view, purine disorders may be classified according to the clinical syndromes they determine: hyperuricemia and gout (Table 3-1), nephrolithiasis, immunodeficiency, anemia, diseases of the peripheral and central nervous systems, and myopathies (Table 3-2).

What is purine degradation?

Purine nucleotide degradation refers to a regulated series of reactions by which human purine ribonucleotides and deoxyribonucleotides are degraded to uric acid in humans. Two major types of disorders occur in this pathway.

What are purine examples?

Examples of structures of purines: (1) adenine; (2) hypoxanthine; (3) guanine (G). Pyrimidines: (4) uracil; (5) cytosine (C); (6) thymine (T). Nucleosides: (7) adenosine (A); (8) uridine (U). Nucleotides: (9) 3′,5′-cAMP; (10) adenosine 5′-triphosphate.

What is involved in purine nucleotide metabolism?

The de novo purine biosynthetic pathway uses six enzymes to catalyze the transformation of phosphoribosylpyrophosphate (PRPP) into inosine 5′-monophosphate (IMP) via 10 highly conserved steps (orange). Purine salvage (green) recycles hypoxanthine, inosine, and adenine as substrates to generate purine nucleotides.

What causes an overproduction of purines?

Diet: A diet rich in high-purine meats, organ foods, and legumes can result in an overproduction of uric acid. Increased nucleic acid turnover: This may be observed in persons with hemolytic anemia and hematologic malignancies such as lymphoma, myeloma, or leukemia.

What is the end product of purine metabolism?

Uric acid is the end product of purine metabolism in humans.

What are the products of purine degradation?

Uric acid, a product of purine metabolism, is degraded in most mammals by the hepatic enzyme urate oxidase (uricase) to more highly soluble allantoin, which is freely excreted in the urine.

Where does purine degradation occur?

Purine degradation. In the animal body, nucleic acids are constantly being degraded and re synthesized. The degradation process follows the route: The degradation of dietary (exogenous) nucleic acids to nucleosides and bases occurs mainly in the small intestinal lumen.

What are the 2 purines?

Nitrogenous bases present in the DNA can be grouped into two categories: purines (Adenine (A) and Guanine (G)), and pyrimidine (Cytosine (C) and Thymine (T)). These nitrogenous bases are attached to C1′ of deoxyribose through a glycosidic bond. Deoxyribose attached to a nitrogenous base is called a nucleoside.

Are eggs high in purines?

Eggs are a good protein source for people with gout, because eggs are naturally low in purines.

What enzymes break down purines?

This system is an enzyme mixture that, at present, consists of 4 purine-degrading enzymes: adenine deaminase, guanine deaminase, xanthine oxidoreductase and urate oxidase, which simultaneously break down purines to a water-soluble 5-hydroxyisourate.

How is purine biosynthesis regulated?

Nucleotide biosynthesis is regulated by feedback inhibition in a manner similar to the regulation of amino acid biosynthesis (Section 24.3). The synthesis of purine nucleotides is controlled by feedback inhibition at several sites (Figure 25.16).

How are disorders of purine and pyrimidine metabolism related?

A number of disorders of purine metabolism lead to immunodeficiency; these include adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency. Marked susceptibility to infection is also seen in disorders of pyrimidine metabolism, classically in orotic aciduria, but also in pyrimidine nucleotide depletion syndrome.

Which is the end product of complete catabolism of purines?

The end product of complete catabolism of purines is uric acid; catabolism of pyrimidines produces citric acid cycle intermediates. There are a number of pyrimidine metabolism disorders. See also Approach to the Patient With a Suspected Inherited Disorder of Metabolism.

Are there any drugs that inhibit purine metabolism?

On the other hand, certain drugs may also inhibit enzymes of the purine nucleotide degradation pathway or may modify renal uric acid excretion. Enzymopathies may be classified into two main groups: overactivity and deficiency, the last being, by far, the most frequent.

Where does purineendogenous come from in the body?

Sources of purineENDOGENOUS• They may be synthesized DE NOVO from small moleculesEXOGENOUS• They may be derived from the breakdown of ingested nucleic acid,mostly from cell-rich meat• Plant diets generally poor in purinesMarch 21, 2013 GKM/MUSOM/NSP 210:PATH