apyrase activity
Definition
Target type: molecularfunction
Catalysis of the reaction: a ribonucleoside 5'-triphosphate + 2 H2O = a ribonucleoside 5'-phosphate + 2 phosphate. This reaction consists of two distinct successive phosphate-releasing steps, with NDPs as intermediates. Apyrases are active against both di- and triphosphate nucleotides (NDPs and NTPs) and hydrolyze NTPs to nucleotide monophosphates (NMPs). [EC:3.6.1.5]
Apyrase activity refers to the enzymatic hydrolysis of nucleoside triphosphates (NTPs), specifically ATP and ADP, into nucleoside monophosphates (NMPs) and inorganic phosphate (Pi). This catalytic process involves the sequential removal of two phosphate groups from the NTP molecule. Apyrases are commonly found in diverse organisms, including bacteria, plants, and animals, and they play crucial roles in a variety of cellular functions.
The molecular function of apyrase activity can be further categorized as follows:
**1. ATP hydrolysis:** Apyrases possess the ability to cleave the terminal phosphate group of ATP, generating ADP and Pi. This step is essential for energy metabolism and cellular signaling pathways.
**2. ADP hydrolysis:** Apyrases can further hydrolyze ADP into AMP and Pi. This process serves to regulate ADP levels, which are essential for maintaining cellular energy homeostasis.
**3. Regulation of cellular processes:** By controlling the levels of ATP and ADP, apyrases play a role in regulating various cellular processes, including:
* **Signal transduction:** Apyrases can modulate the activity of intracellular signaling pathways by influencing the levels of ATP and ADP, which act as second messengers.
* **Cell growth and differentiation:** Apyrases can influence cell proliferation and differentiation by regulating ATP and ADP levels.
* **Immune response:** Apyrases have been implicated in regulating immune responses by modulating the activity of immune cells.
* **Vascular function:** Apyrases can influence vascular tone and blood flow by controlling the levels of ATP and ADP, which are involved in vascular smooth muscle relaxation and contraction.
**4. Extracellular functions:** Apyrases are also found extracellularly, where they play a role in:
* **Platelet aggregation:** Apyrases can inhibit platelet aggregation by hydrolyzing ADP, which is a key mediator of platelet activation.
* **Inflammation:** Apyrases have been shown to inhibit inflammation by degrading pro-inflammatory mediators, such as ATP.
In summary, apyrase activity is a crucial enzymatic process involved in the hydrolysis of ATP and ADP, with profound implications for cellular energy metabolism, signal transduction, and a wide range of physiological functions.'
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Proteins (4)
| Protein | Definition | Taxonomy |
|---|---|---|
| Ectonucleoside triphosphate diphosphohydrolase 1 | An ectonucleoside triphosphate diphosphohydrolase 1 that is encoded in the genome of cow. [OMA:O18956, PRO:DNx] | Bos taurus (cattle) |
| Ectonucleoside triphosphate diphosphohydrolase 8 | An ectonucleoside triphosphate diphosphohydrolase 8 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q5MY95] | Homo sapiens (human) |
| Ectonucleoside triphosphate diphosphohydrolase 1 | An ectonucleoside triphosphate diphosphohydrolase 1 that is encoded in the genome of human. [PRO:WCB, UniProtKB:P49961] | Homo sapiens (human) |
| Ectonucleoside triphosphate diphosphohydrolase 3 | An ectonucleoside triphosphate diphosphohydrolase 3 that is encoded in the genome of human. [PRO:DNx, UniProtKB:O75355] | Homo sapiens (human) |
Compounds (3)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| suramin | suramin : A member of the class of phenylureas that is urea in which each of the amino groups has been substituted by a 3-({2-methyl-5-[(4,6,8-trisulfo-1-naphthyl)carbamoyl]phenyl}carbamoyl)phenyl group. An activator of both the rabbit skeletal muscle RyR1 and sheep cardiac RyR2 isoform ryanodine receptor channels, it has been used for the treatment of human African trypanosomiasis for over 100 years. Suramin: A polyanionic compound with an unknown mechanism of action. It is used parenterally in the treatment of African trypanosomiasis and it has been used clinically with diethylcarbamazine to kill the adult Onchocerca. (From AMA Drug Evaluations Annual, 1992, p1643) It has also been shown to have potent antineoplastic properties. | naphthalenesulfonic acid; phenylureas; secondary carboxamide | angiogenesis inhibitor; antinematodal drug; antineoplastic agent; apoptosis inhibitor; EC 2.7.11.13 (protein kinase C) inhibitor; GABA antagonist; GABA-gated chloride channel antagonist; purinergic receptor P2 antagonist; ryanodine receptor agonist; trypanocidal drug |
| zidovudine | zidovudine : A pyrimidine 2',3'-dideoxyribonucleoside compound having a 3'-azido substituent and thymine as the nucleobase. Zidovudine: A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by an azido group. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is a potent inhibitor of HIV replication, acting as a chain-terminator of viral DNA during reverse transcription. It improves immunologic function, partially reverses the HIV-induced neurological dysfunction, and improves certain other clinical abnormalities associated with AIDS. Its principal toxic effect is dose-dependent suppression of bone marrow, resulting in anemia and leukopenia. | azide; pyrimidine 2',3'-dideoxyribonucleoside | antimetabolite; antiviral drug; HIV-1 reverse transcriptase inhibitor |
| arl-67156 | 6-N,N-diethyl-beta,gamma-dibromomethylene-D-ATP: an inhibitor of ecto-ATPase |