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

---

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

19F nuclear magnetic resonance (NMR) spectroscopy has been used to study a fully active E. coli fluorotyrosine alkaline phosphatase. The fluorotyrosine resonances provide sensitive probes of the conformational states of the protein. They were used to follow the addition of zinc or cobalt to the apoprotein, and the titration of the protein with inorganic phosphate or the inhibitor 2-hydroxy-5-nitrobenzylphosphonate. The results indicate that 2 molecules of inorganic phosphate per dimer of alkaline phosphatase are required to complete a general conformational change in the protein involving perturbations to the environment of several tyrosines. Spectra of the cobalt enzyme indicate that on specific tyrosine per subunit may be near the metal site. The 19F NMR results, combined with the 31P NMR results in the accompanying paper, lead directly to the conclusion that dissociation of noncovalently bound inorganic phosphate from the enzyme is the rate-limiting process in enzyme catalysis at high pH. The local environment of the individual fluorotyrosines is also discussed.
...
PMID:Fluorine-19 nuclear magnetic resonance study of fluorotyrosine alkaline phosphatase: the influence of zinc on protein structure and a conformational change induced by phosphate binding. 0 91

Ultraviolet difference spectra are produced by the binding of divalent metal ions to metal-free alkaline phosphatase (EC 3.1.3.1). The interaction of the apoprotein with Zn2+, Mn2+, Co2+ and Cd2+, which induce the tight binding of one phosphate ion per dimer, give distinctly different ultraviolet spectra changes from Ni2+ and Hg2+ which do not induce phosphate binding. Spectrophotometric titrations at alkaline pH of various metallo-enzymes reveal a smaller number of ionizable tyrosines and a greater stability towards alkaline denaturation in the Zn2+- and Mn2+-enzymes than in the Ni2+-, Hg2+- and apoenzymes. The Zn2+- and Mn2+-enzymes have CD spectra in the region of the aromatic transitions that are different from the CD spectra of the Ni2+-, Hg2+- and apoenzymes. Modifications of arginines with 2,3-butanedione show that a smaller number of arginine residues are modified in the Zn2+-enzyme than in the Hg2+-enzyme. The presented data indicate that alkaline phosphatase from Escherichia coli must have a well-defined conformation in order to bind phosphate. Some metal ions (i.e. Zn2+, Co2+, Mn2+ and Cd2+), when interacting with the apoenzyme, alter the conformation of the protein molecule in such a way that it is able to interact with substrate molecules, while other metal ions (i.e. Ni2+ and Hg2+) are incapable of inducing the appropriate conformational change of the apoenzyme. These findings suggest an important structural function of the first two tightly bound metal ions in enzyme.
...
PMID:Metal ion-induced conformational changes in Escherichia coli alkaline phosphatase. 1 23

3 preparations of 17beta-estradiol and norethisterone acetate were administered to 34 climacteric and 175 postmenopausal women to treat climacteric symptoms and symptoms of estrogen deficiency. 56 women were treated with trisekvens (Group 1), 131 with trisekvens forte (Group 2), and 22 with estrofem forte (Group 3). Triglycerides, cholesterol, calcium, sodium and potassium ions, alkaline phosphatase, creatinine, glucose, protein, albumin, haptoglobin, zinc sulphate, iron, TIBC, bilirubin, ALAT and ASAT, and follicle stimulating hormone (FSH), luteinizing hormone (LH), and low polar estrogens (LPE) were measured. All patients exhibited lowered S-cholesterols which reverted to normal after 6 months treatment. S-triglycerides were unchanged except in Group 1 patients where there was a slight increase after 24 months use (p .01). Serum FSH and LH decreased during treatment and this decrease was most pronounced in Groups 2 and 3. Serum LPE levels increased in Group 1, for climacteric women, to normal luteal values and in postmenopausal women to proliferation values. In groups 2 and 3, serum LPG for postmenopausal women reached luteal values. Climacteric symptoms disappeared with therapy and there was an improvement in symptoms caused by estrogen deficiency. 34 patients discontinued treatment, 14 changing to another preparation. These preparations were well tolerated with few side effects.
...
PMID:Treatment of climacteric and postmenopausal women with 17-beta-oestradiol and norethisterone acetate. 60 3

Kidney alkaline phosphatase was purified to homogeneity. It is a glycoprotein of about 172,000 molecular weight. Analyses of the subunit structure by sedimentation equilibrium in 6 M guanidine hydrochloride and by gel electrophoresis in sodium dodecyl sulfate indicate that the alkaline phosphatase is a dimer comprising two very similar or identical subunits of about 87,000 molecular weight. The native enzyme contains 4.5 +/- 0.2 g atoms of zinc per mol of protein. Reconstitution experiments from the apophosphatase show that binding of 4 Zn2+ per mol of dimer is essential for full activity. The kinetic data of Zn2+ binding to the apoprotein require at least a two-step mechanism, in which one of the steps corresponds to a conformational change within the enzyme. This paper also presents data concerning amino acid composition, sugar content, enzyme stability, absorbance index, and sedimentation velocity.
...
PMID:Bovine kidney alkaline phosphatase. Purification, subunit structure, and metalloenzyme properties. 115 Jun 70

The expression and inducibility of cytochrome P450IA1 isozyme was investigated in the human carcinoma cell line Caco-2 cultured between days 7 and 35 in the absence or the presence of various enzyme inducers such as 3-methylcholanthrene, beta-naphthoflavone (beta NF), dioxin, isosafrole, rifampycin, dexamethasone or phenobarbital. 7-Ethoxyresorufin O-deethylase activity (EROD) was maximal at day 25 when the differentiation of Caco-2 cells, characterized by the level of the brush border associated enzymes such as sucrase isomaltase and alkaline phosphatase, was higher. The inducibility of this enzyme activity was found to be maximal when cells were treated between days 7 and 10. After a 3-day treatment of Caco-2 cells with 50 microM beta NF, EROD achieved 36.6 +/- 14.6 pmol/min/mg compared to 2.5 +/- 1.1 pmol/min/mg in untreated cells. This enzyme activity appeared to be supported only by P450IA1 isozyme because: 1) EROD was quantitatively inhibited by alpha-naphthoflavone, a P450IA1-specific inhibitor; otherwise, phenacetin O-deethylation was completely abolished in the presence of alpha-naphthoflavone and not by furafylline, a P450IA2-specific inhibitor; 2) EROD was induced after treatment with 3-methylcholanthrene, beta NF and dioxin, which are P450IA1 inducers, but not by isosafrole, a P450IA2-specific inducer; 3) cytochrome P450IA1 apoprotein could be immunodetected by antibodies directed against rabbit cytochrome P450-LM6, orthologous to P450IA1, in polycyclic hydrocarbon-treated cells; 4) under the latter conditions, P450IA1 mRNA accumulation was specifically detected, but not P450IA2 mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Regulation of cytochrome P450IA1 gene expression in a human intestinal cell line, Caco-2. 146 46

We demonstrated the utility of Escherichia coli alkaline phosphatase, encoded by phoA, as a reporter molecule for genetic fusions in Rhodobacter sphaeroides. A portion of the R. sphaeroides cycA gene was fused to phoA, yielding a fusion protein comprising the putative signal sequence and first 10 amino acids of the cytochrome c2 apoprotein joined to the sixth amino acid of alkaline phosphatase. The fusion protein was efficiently transported to the periplasm of R. sphaeroides as determined by enzyme activity, Western immunoblot analysis, and immunogold electron microscopy. We also documented the ability of an R. sphaeroides mutant, RS104, with gross defects in photosynthetic membrane morphology to efficiently recognize and translocate the fusion protein to the periplasmic compartment. The inclusion of 500 base pairs of R. sphaeroides DNA in cis to the cycA structural gene resulted in a 2.5-fold increase in alkaline phosphatase activity in photosynthetically grown cells compared with the activity in aerobically grown cells, demonstrating that the fusion protein is regulated in a manner similar to that of cytochrome c2 regulation. We also constructed two pUC19-based plasmids suitable for the construction of translational fusions to phoA. In these plasmids, translational fusions of phoA to the gene under consideration can be made in all three reading frames, thus facilitating construction and expression of fusion protein systems utilizing phoA.
...
PMID:Construction, expression, and localization of a CycA::PhoA fusion protein in Rhodobacter sphaeroides and Escherichia coli. 255 61

To examine the role of lipid metabolism in the growth and function of osteoblast-like cells, we studied ROS 17/2.8 osteosarcoma cells and primary cultures of rat calvarial osteoblasts during growth in a serum-free medium supplemented by purified human lipoproteins or by liposomes. Increase in ROS cell number was measured in sparse (1-5 X 10(3)/cm2) cultures over 6-8 days. Liposomes (0-300 micrograms/ml) and high (HDL), low (LDL), and very low density (VLDL) lipoprotein fractions (0-300 micrograms apoprotein) markedly stimulated cell growth. Cells plated at 5 X 10(3)/cm2 achieved growth rates in the presence of LDL or HDL comparable to 10% fetal bovine serum. Serum-free culture with exogenous lipid maintained the response of cell cyclic AMP accumulation to parathyroid hormone. Cyclic AMP response to parathyroid hormone was enhanced by glucocorticosteroid, and was attenuated by 1,25-dihydroxyvitamin D (1,25(OH)2D) with an EC50 (10(-10) M) comparable to that previously observed in serum-cultured cells (J. Biol. Chem. 258:736, 1985). 1,25(OH)2D also increased the alkaline phosphatase activity in ROS cells cultured in lipid-supplemented serum-free culture. Lipoproteins or liposomes also markedly enhanced the proliferative response of sparse cultures of normal rat osteoblasts to polypeptide mitogens.
...
PMID:Growth of rat osteoblast-like cells in a lipid-enriched culture medium and regulation of function by parathyroid hormone and 1,25-dihydroxyvitamin D. 322 57

We studied metabolic and hormonal patterns in 11 patients on hemodialysis for over 10 years (group A) to determine whether some metabolic abnormalities worsen with long-term dialysis or whether a particular endocrine-metabolic pattern discriminates long-term hemodialysis survivors. Data were compared to those of 14 subjects of similar age and sex on dialysis for 1-3 years (group B) and to those measured in the same patients during the 1st year of dialytic treatment. As to glucose metabolism, group A showed elevation of fasting plasma glucose and a decrease of glucose constant decay (K) and insulin production (IIG) values as compared to the 1st year of dialysis. No difference was found between group A now and group B. However in the 1st year of dialysis group A showed significantly higher K values than group B. As regards lipid metabolism, group A presented higher alpha-lipoprotein values and high-density lipoprotein-cholesterol/cholesterol, high-density lipoprotein-cholesterol/apoprotein A, and apoprotein A/apoprotein B ratios, while low-density lipoprotein-cholesterol and apoprotein B values and beta/alpha-lipoprotein ratio were lower. These data demonstrate less vascular risk in group A. We explain these results as depending on natural selection. Multivariate analysis of survival confirmed that survival in hemodialysis patients is influenced negatively by glucose and lipid metabolism abnormalities. As to Ca-P metabolism, group A showed higher carboxy-terminal parathyroid hormone and alkaline phosphatase values than group B. However, these data may be superimposed to those determined in the same patients in 1981, when we began the regular use of 1 alpha,25-(OH)2-vitamin D3.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Metabolic and hormonal assessment of patients on maintenance hemodialysis for 10 years or more and their importance in long-term survival. 328 86

The cleavage of an amino-terminal decapeptide from Escherichia coli alkaline phosphatase has been previously described (Roberts, C. H., and Chlebowski, J. F. (1984) J. Biol. Chem. 259, 729-733) by this laboratory. The modest reduction in specific activity of the modified enzyme is paralleled by an apparent alteration in the Zn(II) affinity at one of the three active center metal ion binding sites. In contrast to the behavior of the native enzyme, formation of the metal-free apoprotein results in an irreversible loss of catalytic activity; phosphohydrolase activity is not restored on addition of Zn(II) and Mg(II). Differential scanning calorimetry and velocity sedimentation data indicate that the apo form of the modified enzyme exists as a monomer form which, while capable of binding Zn(II) does not readily reassociate to active dimer. Processive cleavage of the amino termini of the dimer by trypsin results in the transient formation of a hybrid dimer consisting of cleaved and uncleaved subunits. This species can be directly observed and isolated by taking advantage of the differential chromatographic mobility of the native "isozymes" and the resulting products. Coupled with improved procedures for the preparation of the modified protein, these data indicate that the amino-terminal modification results in alterations in the subunit interface domain and provides a species (the hybrid dimer) for the investigation of the propagation of these effects.
...
PMID:Trypsin-modified alkaline phosphatase. Formation of apoenzyme monomer and hybrid dimer. 388

The reaction of alkaline phosphatase (APase) with the complexes of myo-inositol hexakisphosphate (IHP) and various cations at pH 7.2 results in a decrease in activity. Singly, neither IHP nor metal ions induce such changes. IHP-Mn(II) complexes were the least effective. Using the ions of nickel or cadmium, activity was reduced by > 95%. A similar large decrease (> 99%) was seen previously in the reaction of APase with IHP-Cu(II) complexes. With Co(II) and IHP as reactants, the activity was reduced to 10-12% of that of the native enzyme. When the apoprotein, prepared by reaction of the enzyme with either EDTA or 1,10-phenanthroline, was titrated with Co(II), the activity was equal to that resulting from the reaction of the enzyme with IHP-Co(II) complexes. Titration with zinc restored 95% of the original activity. The products are metal-substituted derivatives in which the resident catalytic (A-site) zinc ions, at least, are replaced by the cation of the IHP complex that was used. The rates of such reactions were fastest with the complexes of Cu(II) and Cd(II) (0.12 min-1), less so with Co(II) as the ion (0.056 min-1), and slowest with complexes of nickel and manganese (0.01 min-1). In every case, the rate of reaction, but not its extent of change, was inhibited by zinc ions that reduced rate constants to 0.0014-0.0054 min-1. Magnesium ions had no effect. Likewise, Mn(II), with but one exception, did not affect the reactions. When present along with IHP-Ni(II) complexes, the rate was increased and the enzyme activity further decreased. If Zn(II) was also present, this enhancement was eliminated. All changes in enzyme activity were reversible by treatment with EDTA followed by reconstitution with zinc. Approximately 95% conversion to the original activity could be attained. Reactivation of modified APase preparation also could be attained, in some cases, by pre-incubation with Zn(II) at pH 8. For example, conversion of the Cd(II)-substituted APase to the zinc enzyme was rapid and complete in 15 min. With the Cu(II)-substituted derivative, reactivation was much slower. Incubation with zinc ions had little or no effect on other Me(II)-substituted APase preparations. Co-APase and Cu-APase, prepared from the apoprotein, behaved similarly to their respective "counterpart product" of the appropriate metal ion-exchange reaction. In contrast, Co-APase, but not Cu-APase, could be converted to the zinc enzyme by incubation with IHP-Zn(II) complexes at pH 7.2. The reaction rate of the various metal-substituted APase preparations with EDTA varied with the IHP-Me(II) used in its formation.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Reaction of the coordinate complexes of inositol hexaphosphate with first row transition series cations and Cd(II) with calf intestinal alkaline phosphatase. 776 85


1 2 Next >>

---