Apyrase

Related Reading

Apyrase is an enzyme that can dephosphorylate the corresponding substrate, that is, by hydrolyzing the phosphate monoester to remove the phosphate group on the substrate molecule, and generate phosphate ions and free hydroxyl groups. The role of apyrase is opposite to that of kinase, which is a phosphorylase that can use energy molecules, such as ATP, to add phosphate groups to the corresponding substrate molecules.

Acid apyrases

Most plant acid apyrases have no obvious substrate specificity. The substrates that can be hydrolyzed include RNA, DNA, 3-phosphoglycerate, and hexose phosphate. In in vitro experiments, the enzyme activity of acid apyrase purified from arabidopsis thaliana and tomato was inhibited by the high concentration of Pi in the buffer. Further research found that the Pi produced by acid apyrase hydrolysis can negatively inhibit most acid apyrase activity.

Acid apyrase activity and the effectiveness of organic phosphorus

Under phosphorus starvation conditions, plants are induced to secrete acid apyrase; on the other hand, the increase in acid apyrase activity of plant roots can hydrolyze and release organic phosphorus compounds in the soil for plant growth. In plants, acid apyrase mainly accumulates in vacuoles. A large number of studies have shown that acid apyrase plays a very important role in regulating plant phosphorus nutrition, and it also plays a very important role in the metabolism and reuse of organic phosphorus. Its activity directly affects the effectiveness of organophosphorus.

Gene control of acid apyrase secretion

Secretion of acid apyrase is a common adaptive response to low phosphorus stress in plants, and this adaptive change is also the result of the coordinated expression of phosphorus deficiency in response to genes. By responding to the direct or indirect effects of gene products, it promotes phosphorus Absorption, transport and effective utilization, research on acid apyrase genes has made great progress.

Alkaline apyrase

Alkaline apyrase is a non-specific phosphomonoesterase, which can catalyze the hydrolysis reaction of almost all phosphate monoesters to generate inorganic phosphoric acid and corresponding alcohols, phenols, sugars, etc., and can also catalyze the transfer reaction of phosphate groups. AP is also a phosphite-dependent hydrogenase.

Applications

Alkaline apyrase has a wide range of uses in the fields of medicine and molecular biology. In clinical medicine, measuring the activity of alkaline apyrase in serum has become an important means of diagnosis and monitoring of many diseases. AP is mainly used for the examination of obstructive jaundice, primary liver cancer, secondary liver cancer, cholestatic hepatitis, etc. When suffering from these diseases, liver cells overproduce alkaline apyrase, which enters the blood through the lymphatic tract and sinusoids. Due to the obstruction of bile excretion in the intrahepatic biliary tract, the reflux caused a significant increase in serum alkaline apyrase. The obvious increase of intestinal alkaline apyrase in the blood can be seen in various intestinal diseases. There are also reports in the literature that certain digestive system diseases, autoimmune diseases and malignant tumors can also appear in the blood of immunoglobulin complex alkaline apyrase.

Reference

1. Smith TM.; et al. Cloning, expression, and characterization of a soluble calcium-activated nucleotidase, a human enzyme belonging to a new family of extracellular nucleotidases. Arch. Biochem. Biophys. 2002, 406 (1): 105–15.