ADENOZINTRIFOSFATAZA (synonym: adenilpirofosfataza, apyrases, ATP-ases, ATF-ATF-fosfogidrolazy) — group of the enzymes which are chipping off the remains phosphoric to - you from adenosine triphosphoric to - you are (ATP). Belong to the class of hydrolases (see).
And. split vysokoergichesky bonds of ATP (see Vysokoergichesky connections), releasing at the same time a large amount of energy, and provide use of this energy for processes of life activity: the movements, biosynthesis of a number of connection, transport of ions I other substances through membranes, etc. And. are eurysynusic in fabrics of all organisms. Membrane structures, plasmatic and nuclear membranes, an endoplasmic reticulum, mitochondrions are especially rich with them. Many And., found at a research of bodies and fabrics out of an organism, actually are ATF-fosfotransferazami, or kinases (see), i.e. the enzymes moving the remains phosphoric to - you from ATP on other connections.
Typical representative A., and acting in the alkalescent environment, the muscular adenozintrifosfataza — sokratitelny protein of muscles is activated by calcium ions (myosin) which reduction is connected with splitting of ATP. Other type A. the hl meets. obr. in mitochondrions, it is activated by ions of magnesium and it is most active in the neutral environment. In mitochondrions this And. is in the so-called fungoid outgrowths located on an inner membrane of mitochondrions. This look And. presumably identify with the so-called coupling factor of F1 necessary for oxidizing phosphorylation in mitochondrions (see Phosphorylation), i.e. the biological role it consists in phosphorylation of adenosinediphosphate.
Both types of enzymes A. are ATF-fosfogidrolazami and chip off from ATP one rest phosphoric to - you with formation of adenosinediphosphate on the equation:
ATP + H 2 O = ADF + ortho-phosphate.
In plants the apyrase activated by calcium ions and which is chipping off from ATP two rests phosphoric to - you with release adenylic (adenosinemonophosphoric) to - you on the equation is eurysynusic ATF-difosfogidrolaza, or:
ATP + 2H 2 O = AMF + 2 ortho-phosphates.
Some And. (ATF-pirofosfogidrolazy, or adenilpirofosfataza) chip off the rest of a pyrophosphate from ATP:
ATP + H 2 O = AMF + pyrophosphate.
Is described a little And., the certain substances localized in biological membranes and connected with transport. So, and, perhaps, in an endoplasmic reticulum of kidneys and a brain contains in a plasma membrane And., activated by ions of sodium p potassium in the presence of ions of magnesium (sodium - potassium - activated And.), specifically suppressed by heart alkaloid strophanthin G (oubainy). This And. provides functioning of «sodium pompe» (see Transport of ions) thanks to what ion concentration of sodium in various fabrics (a liver, erythrocytes, etc.) is much lower, than in the environment (blood plasma). And, apparently, in some other fabrics contain in an epithelium of a mucous membrane of intestines connecting calcium and activated by bottoms of calcium A., which cause transport of calcium ions and are activated by vitamin D. In various biological membranes, apparently, there are also others And., specific to transport of amino acids, nucleotides and some other biologically important substances. Specificity And. concerning substrate on absolute; many And. split also other nukleozidtrifosfata, e.g. inozintrifosfat, uridinetriphosphate, guanozintrifosfat, cytidinetriphosphate, dezoksinukleozidtrifosfata (dezoksi-ATF), etc. Absence or insufficiency of these or those And. leads to pathological disturbances. So, insufficiency is known And. erythrocytes, activated oubainy, shown in a special type of hemolitic anemia and muscular dystrophy.
Bibliography: Lisovsky I. P. Adenozintrifosfataza of cellular membranes and transfer of ions, in book: Usp. biol, chemical, under the editorship of B. N. Stepanenko, t. 8. page 93, M., 1967, bibliogr.; Poglazov B. F. Structure and functions of sokratitelny proteins, page 14, M., 1965; Morton R. To. Phosphatases, Comprchens. Biochem., v. 16, p. 5G), 1965, bibliogr. I. B. Zbarsky.