File Name: structure and mechanism of alkaline phosphatase .zip
Alkaline phosphatase is an enzyme commonly expressed in almost all living organisms. Alkaline phosphatase also seems to be one of the key markers in the identification of pluripotent embryonic stem as well as related cells. However, alkaline phosphatases exist in some isoenzymes and isoforms, which have tissue specific expressions and functions. Here, the role of alkaline phosphatase as a stem cell marker is discussed in detail.
Recent years have seen an increase in the number of studies focusing on alkaline phosphatases APs , revealing an expanding complexity of function of these enzymes. IAP regulates fatty acid absorption and has been implicated in the regulation of diet-induced obesity and metabolic syndrome. IAP and TNAP can dephosphorylate bacterial-derived lipopolysaccharide, and IAP has been identified as a potential regulator of the composition of the intestinal microbiome, an evolutionarily conserved function. Endogenous and recombinant bovine APs and recombinant hAPs are currently being explored for their potential as pharmacological agents to treat AP-associated diseases and mitigate multiple sources of inflammation. Continued research on these versatile proteins will undoubtedly provide insight into human pathophysiology, biochemistry, and the human holobiont. Alkaline phosphatases APs belong to a superfamily of proteins EC 3.
The alkaline phosphatase AP is a bi-metalloenzyme of potential applications in biotechnology and bioremediation, in which phosphate monoesters are nonspecifically hydrolysed under alkaline conditions to yield inorganic phosphate. The hydrolysis occurs through an enzyme intermediate in which the catalytic residue is phosphorylated. The reaction, which also requires a third metal ion, is proposed to proceed through a mechanism of in-line displacement involving a trigonal bipyramidal transition state. Stabilizing the transition state by bidentate hydrogen bonding has been suggested to be the reason for conservation of an arginine residue in the active site. We report here the first crystal structure of alkaline phosphatase purified from the bacterium Sphingomonas. The crystal structure reveals many differences from other APs: 1 the catalytic residue is a threonine instead of serine, 2 there is no third metal ion binding pocket, and 3 the arginine residue forming bidentate hydrogen bonding is deleted in SPAP. A lysine and an aspargine residue, recruited together for the first time into the active site, bind the substrate phosphoryl group in a manner not observed before in any other AP.
Each monomer contains five cysteine residues, two zinc atoms and one magnesium atom crucial to its catalytic function, and it is optimally active at alkaline pH environments. ALP has the physiological role of dephosphorylating compounds. The enzyme is found across a multitude of organisms, prokaryotes and eukaryotes alike, with the same general function but in different structural forms suitable to the environment they function in. Alkaline phosphatase is found in the periplasmic space of E. This enzyme is heat stable and has its maximum activity at high pH.
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Alkaline phosphatase in serum consists of 4 structural genotypes: the liver-bone-kidney type, the intestinal type, the placental type, and the variant from the germ cells. It occurs in osteoblasts, hepatocytes, leukocytes, the kidneys, spleen, placenta, prostate, and the small intestine. The liver-bone-kidney type is particularly important. A rise in the alkaline phosphatase occurs with all forms of cholestasis, particularly with obstructive jaundice. It is also elevated in diseases of the skeletal system, such as Paget disease, hyperparathyroidism, rickets and osteomalacia, as well as with fractures and malignant tumors. A considerable rise in the alkaline phosphatase activity is sometimes seen in children and juveniles. It is caused by increased osteoblast activity following accelerated bone growth.
Escherichia coli alkaline phosphatase EC 3. We investigated the nature of th We investigated the nature of the primary nucleophile, fulfilled by the deprotonated Ser, in the catalytic mechanism by mutating this residue to glycine, alanine and cysteine. In order to investigate the structural details of the altered active site, the enzymes were crystallized and their structures determined. The enzymes crystallized in a new crystal form corresponding to the space group P Each structure has phosphate at each active site and shows little departure from the wild-type model. For the SG and SA enzymes, the phosphate occupies the same position as in the wild-type enzyme, while in the SC enzyme it is displaced by 2.
Our knowledge of the structure and function of alkaline phosphatases has increased greatly in recent years. The crystal structure of the human placental isozyme has enabled us to probe salient features of the mammalian enzymes that differ from those of the bacterial enzymes. The availability of knockout mice deficient in each of the murine alkaline phosphatase isozymes has also given deep insights into their in vivo role. This has been particularly true for probing the biological role of bone alkaline phosphatase during skeletal mineralization. Due to space constraints this mini-review focuses exclusively on structural and functional features of mammalian alkaline phosphatases as identified by crystallography and probed by site-directed mutagenesis and kinetic analysis.
of Escherichia coli alkaline phosphatase (AP) involving two- metal ion catalysis is the X-ray crystal structures of the covalent phospho-enzyme intermediate of.
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А у ее клиентов по крайней мере есть деньги. Они ее не бьют, им легко угодить.
Наверное, за ним тянется красный след на белых камнях. Он искал глазами открытую дверь или ворота - любой выход из этого бесконечного каньона, - но ничего не. Улочка начала сужаться.
Он профессор лингвистики, а не физики. - Атакующие линии готовятся к подтверждению доступа.
Если даже он каким-то образом откроет лифт и спустится на нем вместе со Сьюзан, она попытается вырваться, как только они окажутся на улице. Хейл хорошо знал, что этот лифт делает только одну остановку - на Подземном шоссе, недоступном для простых смертных лабиринте туннелей, по которым скрытно перемешается высокое начальство агентства. Он не имел ни малейшего желания затеряться в подвальных коридорах АНБ с сопротивляющейся изо всех сил заложницей. Это смертельная ловушка. Если даже он выберется на улицу, у него нет оружия.
Я вчера говорил с. Велел ему сегодня не приходить. Он ничего не сказал о том, что поменялся с тобой дежурством.
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