Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We reported previously that a 32-36-kDa osteogenic protein purified from bovine bone matrix is composed of dimers of two members of the transforming growth factor (TGF)-beta superfamily: the bovine equivalent of human osteogenic protein-1 (OP-1) and bone morphogenetic protein-2a, BMP-2a (BMP-2). In the present study, we produced the recombinant human OP-1 (hOP-1) in mammalian cells as a processed mature disulfide-linked homodimer with an apparent molecular weight of 36,000. Examination of hOP-1 in the rat subcutaneous bone induction model demonstrated that hOP-1 was capable of inducing new bone formation with a specific activity comparable with that exhibited by highly purified bovine osteogenic protein preparations. The half-maximal bone-inducing activity of hOP-1 in combination with a rat collagen matrix preparation was 50-100 ng/25 mg of matrix as determined by the calcium content of day 12 implants. Evaluation of hOP-1 effects on cell growth and collagen synthesis in rat osteoblast-enriched bone cell cultures showed that both cell proliferation and collagen synthesis were stimulated in a dose-dependent manner and increased 3-fold in response to 40 ng of hOP-1/ml. Examination of the expression of markers characteristic of the osteoblast phenotype showed that hOP-1 specifically stimulated the induction of alkaline phosphatase (4-fold increase at 40 ng of hOP-1/ml), parathyroid hormone-mediated intracellular cAMP production (4-fold increase at 40 ng of hOP-1/ml), and osteocalcin synthesis (5-fold increase at 25 ng of hOP-1/ml). In long-term (11-17 day) cultures of osteoblasts in the presence of beta-glycerophosphate and L(+)-ascorbate, hOP-1 markedly increased the rate of mineralization as measured by the number of mineral nodules per well (20-fold increase at 20 ng of hOP-1/ml). Direct comparison of TGF-beta 1 and hOP-1 in these bone cell cultures indicated that, although both hOP-1 and TGF-beta 1 promoted cell proliferation and collagen synthesis, only hOP-1 was effective in specifically stimulating markers of the osteoblast phenotype.
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PMID:Recombinant human osteogenic protein-1 (hOP-1) induces new bone formation in vivo with a specific activity comparable with natural bovine osteogenic protein and stimulates osteoblast proliferation and differentiation in vitro. 132 98

We recently purified a 16-kDa cytosolic Cu/Zn superoxide dismutase (CT Cu/Zn-SOD) from Schistosoma mansoni, a human parasite. Three peptide sequences were obtained, one from the unblocked N-terminal and two from internal peptides which were generated by digestions with trypsin and cyanogen bromide. These sequences were aligned to the corresponding sequences of 19 cytosolic Cu/Zn-SODs from various species. Degenerate oligonucleotides were then designed according to the sequence and the position of each peptide. The oligonucleotides were used to amplify a complete cDNA using the polymerase chain reaction with either adult schistosome total RNA or a cercariae lambda gt11 phage cDNA library as the template. The protein encoded by the cDNA has 153 amino acids with a calculated molecular weight of 15,693. It also has 60-65% homology to 19 cytosolic Cu/Zn-SOD from various species. All of the copper/zinc binding sites and SOD activity sites are conserved. Computer analysis predicts that the Cu/Zn-SOD has a pI value of 6.6, which is very close to the experimental results of IEF analysis (6.0 and 6.3). The entire coding sequence from the cDNA was cloned into a bacterial alkaline phosphatase cytosolic expression vector and a large amount of soluble product was expressed and purified to homogeneity. We compared the bacterially expressed Cu/Zn-SOD with the native enzyme derived from schistosomes and found that they are identical by the following criteria: (1) They focus at the same positions on IEF gels; (2) they form dimers in solution as measured by gel filtration; (3) they have the same unblocked N-terminal sequence; (4) they both are enzymatically active with comparable specific activities. The specific activity of the bacterially derived enzyme was increased somewhat (approximately 10%) by incubation with copper and zinc ions.
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PMID:Schistosoma mansoni: cloning of a complementary DNA encoding a cytosolic Cu/Zn superoxide dismutase and high-yield expression of the enzymatically active gene product in Escherichia coli. 142 33

Serum Mn-superoxide dismutase (Mn-SOD) was determined in patients with various liver diseases including 31 patients with primary biliary cirrhosis (PBC), 46 with hepatocellular carcinoma (HCC), 17 with liver cirrhosis (LC), 23 with chronic hepatitis (CH) and 12 patients with obstructive jaundice with an enzyme-linked immunosorbent assay using a specific monoclonal antibody. The serum level in patients with PBC (407 +/- 35 ng/ml, mean +/- SEM; n = 31) was significantly increased (p less than 0.01) compared with those of other liver diseases. Mn-SOD level did not correlate with total bilirubin level, gamma-glutamyl transpeptidase activity, alkaline phosphatase activity, alanine aminotransferase activity, IgM, or with ceruloplasmin level in the sera of the patients. When the patients with PBC were histologically subdivided into four groups according to Scheuer's classification (Scheuer PJ. Primary biliary cirrhosis. In: Scheuer PJ, ed. Liver biopsy interpretation. 3rd ed. London: Bailliere Tindall, 1980:47-56), a high level of serum Mn-SOD was noticed in the early stage as well as in the advanced stage of the disease. Immunoblot analysis confirmed the reactivity and specificity of the monoclonal antibody to the enzyme protein in the patients' sera. Immunostaining of a liver biopsy specimen from the patients with PBC revealed increased expression of the enzyme protein in damaged epithelial cells of interlobular bile ducts, bile ductules, and degenerated hepatocytes. These data suggested that free radicals including superoxide anion are possibly involved in the pathogenesis of the disease and Mn-SOD may play some role in a protection against the superoxide anion.
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PMID:Elevated level of serum Mn-superoxide dismutase in patients with primary biliary cirrhosis: possible involvement of free radicals in the pathogenesis in primary biliary cirrhosis. 168 6

The susceptibility to lipid peroxidation (LPO) of liver, kidneys, brains, lungs, heart, and testes was assessed in rats administered intraperitoneally with various doses of cadmium (Cd). Dose-response studies were carried out with male Long Evans rats (12-week-old; 300 +/- 33 g) injected with 25, 125, 500, and 1250 micrograms Cd/kg as CdCl2 and sacrificed after 24 h. In time-response studies, animals were administered with 25 and 500 micrograms Cd/kg as CdCl2 and sacrificed after 2, 6, 12, 24, and 72 h. Exposure of rats to low and moderate doses of Cd by the intraperitoneal route stimulated LPO in all the tissues investigated as assessed by the measurement of thiobarbituric acid reactive substances (TBARS). Lungs and brain were the most responsive, and these tissues and liver displayed early responses following Cd exposure. Comparison of LPO to various tissue indicators (for liver: alanine aminotransferase (ALT), sorbitol dehydrogenase (SDH), alkaline phosphatase (ALP); for lungs: ALP, gamma-glutamyl transpeptidase (GGT] suggested that low doses of Cd stimulated LPO without any evidence of acute damages. These results suggest that LPO is an early and sensitive consequence of Cd exposure as determined in various organs. Investigation of liver, lungs, and heart antioxidant defense system components (glutathione peroxidase (GPX), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH), superoxide dismutase (SOD] revealed that GPX might be considered as a potential modulator of the Cd-induced LPO reaction in lungs and heart tissues.
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PMID:Studies on lipid peroxidation in rat tissues following administration of low and moderate doses of cadmium chloride. 182 34

Alkaline phosphatase (AP) is a widely distributed non-specific phosphomonoesterase that functions through formation of a covalent phosphoseryl intermediate (E-P). The enzyme also catalyzes phosphoryl transfer reaction to various alcohols. Escherichia coli AP is a homodimer with 449 residues per monomer. It is a metalloenzyme with two Zn2+ and one Mg2+ at each active site. The crystal structure of native E. coli AP complexed with inorganic phosphate (Pi), which is a strong competitive inhibitor as well as a substrate for the reverse reaction, has been refined at 2.0 A resolution. Some parts of the molecular have been retraced, starting from the previous 2.8 A study. The active site has been modified substantially and is described in this paper. The changes in the active site region suggest the need to reinterpret earlier spectral data, and suggestions are made. Also presented are the structures of the Cd-substituted enzyme complexed with inorganic phosphate at 2.5 A resolution, and the phosphate-free native enzyme at 2.8 A resolution. At pH 7.5, where the X-ray data were collected, the Cd-substituted enzyme is predominantly the covalent phosphoenzyme (E-P) while the native Zn/Mg enzyme exists in predominantly noncovalent (E.P) form. Implication of these results for the catalytic mechanism of the enzyme is discussed. APs from other sources are believed to function in a similar manner.
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PMID:Reaction mechanism of alkaline phosphatase based on crystal structures. Two-metal ion catalysis. 201 Sep 19

Platelet-derived growth factor (PDGF) exists as a homodimer or a heterodimer comprising either PDGF-A or PDGF-B subunits, and each isoform occurs in various tissues, including bone. Although the stimulatory effects of PDGF-BB have been studied in cultures of bone cells and intact bone fragments, the influence of other isoforms that may arise locally or systematically in vivo, has not been reported. Therefore recombinant human PDGF-BB, PDGF-AB, and PDGF-AA were evaluated in osteoblast-enriched cultures from fetal rat bone. Within 24 hours these factors produced a graded response in bone cell DNA and protein synthesis, with half-maximal effects at approximately 0.6, 2.1, and 4.8 nM PDGF-BB, PDGF-AB, and PDGF-AA, respectively. Increases in collagen and noncollagen protein synthesis were abrogated when DNA synthesis was blocked with hydroxyurea. Furthermore, each factor reduced alkaline phosphatase activity, PDGF-BB being the most inhibitory. Binding studies with 125I-PDGF-BB or 125I-PDGF-AA and each unlabeled PDGF isoform produced discrete ligand binding and displacement patterns: 125I-PDGF-BB binding was preferentially displaced by PDGF-BB (Ki approximately 0.7 nM), less by PDGF-AB (Ki approximately 2.3 nM) and poorly by PDGF-AA. In contrast, 125I-PDGF-AA binding was measurably reduced by PDGF-AA (Ki approximately 4.0 nM), but was more effectively displaced by PDGF-BB or PDGF-AB (each with Ki approximately 0.7 nM). These studies indicate that each PDGF isoform produces biochemical effects proportional to binding site occupancy and suggest that receptors that favor PDGF-B subunit binding preferentially mediate these results in osteoblast-enriched bone cell cultures.
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PMID:Relative binding and biochemical effects of heterodimeric and homodimeric isoforms of platelet-derived growth factor in osteoblast-enriched cultures from fetal rat bone. 206 62

Cell-associated alkaline phosphatase (ALPase) of Bacteroides gingivalis 381 was found in the outer part of the periplasmic space by using an ultracytochemical procedure. Cell-associated ALPase was solubilized by extraction with 1% Triton X-100, and the solubilized enzyme was purified 904-fold with 5.6% recovery by using affinity column chromatography for mammalian intestinal-form ALPase. The purified enzyme gave a single protein band that corresponded to the enzyme activity band on polyacrylamide gel electrophoresis preparations. A single protein band at a molecular weight of 61,000 was observed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis preparations. The molecular weight of the native enzyme was estimated to be 130,000 by gel filtration with TSK-gel G3000SW. These findings indicate that B. gingivalis ALPase is a homodimer. The optimal pH of the enzyme was between 9.1 and 9.3 in the absence of divalent metal ions and was between 10.1 and 10.3 in the presence of manganese or zinc ions. The apparent km for p-nitrophenylphosphate was 0.037 +/- 0.003 mM (mean +/- standard deviation) at pH 9.2 in the absence of divalent metal ions and 0.22 +/- 0.02 mM at pH 10.2 in the presence of 1 mM manganese ions. Under both of the conditions described above, the purified enzyme was able to hydrolyze casein and O-phosphoserine, suggesting that B. gingivalis ALPase can act as a phosphoprotein phosphatase. ALPase that immunologically cross-reacted with the purified enzyme was found in the extracellular soluble fraction. This means that ALPase is released from the periplasmic space into the culture supernatant as a soluble form.
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PMID:Purification and characterization of alkaline phosphatase of Bacteroides gingivalis 381. 211 73

Intestinal-like alkaline phosphatase was found to be expressed in the intestinal 407 cell line. This enzyme was identified by use of monoclonal antibodies specific for human placental (H7 and HPMS-1) and intestinal alkaline phosphatase (2HIMS-1 and 2HIMS-3) separately. Purification of this isozyme by use of two different monoclonal antibody immunoaffinity chromatographies demonstrates a single protein band on SDS-polyacrylamide gel electrophoresis indicating that this enzyme is not formed as a heterodimer. The apparent monomer subunit molecular weight and the dimer molecular weight of this isozyme were determined to 70000 and 160000, respectively. The enzyme is a homodimer according to molecular weight determinations. Furthermore, this isozyme is neuraminidase sensitive and comparatively heat stable, properties also characteristic for the placental enzyme. Our data suggest that the intestinal-like alkaline phosphatase in the intestinal 407 cell line displays properties intermediate of the intestinal and placental isozymes which may reflect the existence and reexpression of a new primitive isozyme.
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PMID:Evidence for the expression of a primitive intestinal-like alkaline phosphatase in the intestinal 407 cell line. 246 Jan 3

The phosphorylation of Drosophila melanogaster DNA topoisomerase II by purified casein kinase II was characterized in vitro. Under the conditions used, the kinase incorporated a maximum of 2-3 molecules of phosphate per homodimer of topoisomerase II. No autophosphorylation of the topoisomerase was observed. The only amino acid residue modified by casein kinase II was serine. Apparent Km and Vmax values for the phosphorylation reaction were 0.4 microM topoisomerase II and 3.3 mumol of phosphate incorporated per min per mg of kinase, respectively. Phosphorylation stimulated the DNA relaxation activity of topoisomerase II by 3-fold over that of the dephosphorylated enzyme, and the effects of modification could be reversed by treatment with alkaline phosphatase. Therefore, this study demonstrates that post-translational enzymatic modifications can be used to modulate the interaction between topoisomerase II and DNA.
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PMID:Phosphorylation of DNA topoisomerase II by casein kinase II: modulation of eukaryotic topoisomerase II activity in vitro. 298 12

Activities of the enzymes lactase, sucrase, maltase, alkaline phosphatase, and superoxide dismutase (SOD) were measured in mucosa of duodenum and ileum of the rat after 70% resection of mid-small intestine or sham operation (transection). We also measured the concentrations of zinc, copper, and manganese in several tissues to assess trace metal homeostasis postresection. Resection resulted in decreased specific activities of disaccharidases and alkaline phosphatase in duodenum, while specific activities remained unchanged in ileum. Specific activity of total SOD (the sum of Cu-Zn and Mn SOD) and Mn SOD was the same in duodenum after resection but was markedly increased in ileum. Tissue trace metal concentrations changed minimally. Because of postresection mucosal growth, total segmental activity of disaccharidases and alkaline phosphatase was the same in duodenum and increased in ileum of resected compared to transected rats. Segmental activity of total SOD and Mn SOD doubled in duodenum and trebled in ileum of resected as compared to transected rats. Thus, total segmental enzyme activity is maintained or increased postresection by increased enterocyte proliferation rate and mucosal growth.
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PMID:Adaptation of the duodenum and ileum of the rat to mid-gut resection: enzyme activity and trace metal status. 308 Aug 64


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