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)

The polynucleotides poly(U), poly(C), poly(A) and poly(G) have been gamma-irradiated in N2O- and N2O/O2 (4:1)-saturated aqueous solutions. Hydroxyl radicals from the radiolysis of water react with the polynucleotides thereby producing among other lesions strand breaks. Strand breakage is connected with the formation of phosphomonoester end groups. Such end groups have been determined by measuring inorganic phosphate after a three hour incubation at 37 degrees C with acid or alkaline phosphatase. In the absence of oxygen G(phosphomonoester end groups) (in units of mumol J-1) are 0.47 (poly(U)), 0.17 (poly(C)) and less than or equal to 0.04 (poly(A) and poly(G)). In the case of poly(U) and poly(C) on heating the sample for one hour at 95 degrees C prior to incubation with phosphatases the above values increased by 0.14 and 0.07 mumol J-1, resp., whereas such treatment of the purine polynucleotides still did not produce a measurable yield of phosphomonoester end groups. Comparing these values with G values for strand breakage taken from the literature, about two phosphomonoester end groups are formed per strand break in poly(U) while for poly(C) this ratio is about unity. The purine polynucleotides show very low yields of strand breakage in agreement with the negligible phosphomonoester yields. In the presence of oxygen G(phosphomonoester end groups) are 0.46 (poly(U)), 0.21 (poly(C)), and less than or equal to 0.04 (poly(A) and poly(G)). On heating, these values increase, most markedly for poly(U) and poly(C). This is possibly linked to the decomposition of unstable hydroperoxides which are formed in high yields in poly(U) and poly(C) (G = 0.7 and 0.19 mumol J-1, resp.).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The formation of phosphate end groups in the radiolysis of polynucleotides in aqueous solution. 322 34

New lanthanide methods for the histochemical detection of non-specific alkaline phosphatase in the light microscope are described and compared with already existing techniques for the light microscopical demonstration of this enzyme. To avoid formation of insoluble lanthanide hydroxide at alkaline pH citrate complexes with the capture ions cerium, lanthanum and didymium were used. A molar ratio of 11 mM citrate/14 mM capture reagent is proposed. For preincubated sections, pretreatment in chloroform-acetone and fixation in glutaraldehyde, for non-preincubated sections fixation in glutaraldehyde yielded the best results. 4-Methylumbelliferyl and 5-Br-4-Cl-3-indoxyl phosphate were found to be the most suitable substrates. For routine purposes 4-nitrophenyl, 1-naphthyl, 2-naphthyl and 2-glycerophosphate were also sufficient; naphthol AS phosphates were inferior but still suitable. After incubation for 5-60 min at 37 degrees C lanthanide phosphate was converted into lead phosphate which was visualized as lead sulfide. At pH 9.2-9.5 enzyme activity was demonstrated at many sites such as intestinal, uterine, placental, renal and epididymal microvillous zones, plasma membranes of arterial, sinus and capillary endothelial cells, vaginal and urethral epithelium, smooth muscle cells, myoepithelial cells as well as excretory duct cells of salivary and lacrimal glands and in secretory granules of laryngeal glands. In comparison with Gomori's calcium, Mayahara's lead, Burstone's and Pearse's azo-coupling, McGadey's tetrazolium salt and Gossrau's azoindoxyl coupling technique the lanthanide methods detected alkaline phosphatase activities at identical or additional sites depending on the respective procedure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Light-microscopic histochemistry of non-specific alkaline phosphatase using lanthanide-citrate complexes. 323 44

Bone histologies and serum concentrations of calcium, phosphate, alkaline phosphatase, iPTH, 25 OHD, 1,25(OH)2D3, and aluminum were obtained from 113 chronically hemodialyzed patients free of symptoms and signs of renal osteodystrophy. All patients had a pathologic bone histology; in 69.0%, a mixed form with predominant osteitis fibrosa and concomitant osteoidosis. In 30.1%, we found pure hyperosteoidosis, nearly half of these cases showing osseous aluminum deposits. Hyperosteoidosis was much more frequent in women (35.7%) than in men (20.9%), although the prescribed intake of aluminum-containing phosphate binders was the same. It is possible that female hemodialysis patients were more prone to aluminum accumulation or that they had a better compliance in taking the aluminum hydroxide. Serum parameters alone were not very helpful in predicting the underlying bone disease. Mean iPTH concentrations tended to be lower in the patients with hyperosteoidosis than in those with the mixed lesion, but there was wide variation. Serum aluminum was only predictive for aluminum deposits in the bone when concentrations exceeded 100 micrograms/L.
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PMID:Renal osteodystrophy in asymptomatic hemodialysis patients: evidence of a sex-dependent distribution and predictive value of serum aluminum measurements. 381 72

We evaluated the effectiveness of calcium carbonate as a phosphate binder in 19 children with chronic renal failure; ten children were undergoing dialysis therapy (eight maintained by CAPD and two by hemodialysis). Twelve children had previously received aluminum hydroxide, while calcium carbonate was the primary phosphate binder used in seven children. Among all the children, the serum phosphorus level on no phosphate binder was 7.4 +/- 0.9 mg/dL, which decreased significantly (P less than .001) to 5.9 +/- 0.8 mg/dL during calcium carbonate therapy, while the serum calcium, bicarbonate, and creatinine were unchanged. The reduction in the serum phosphorus level occurred while dietary intake of calcium and phosphorus were unchanged, as demonstrated by three-day dietary records. The dose of calcium carbonate required to maintain the serum phosphorus in the normal range varied from 600 mg to 15 g/d (mean 7.4 g/d). Among the 12 children and four others who had received aluminum hydroxide, serum aluminum levels fell from 108.8 +/- 121.8 ng/mL to 36.1 +/- 29.1 ng/mL after aluminum hydroxide was stopped (P less than .05). Serum alkaline phosphatase and parathyroid hormone (PTH) levels during aluminum hydroxide therapy were similar to levels obtained during calcium carbonate therapy, while PTH levels fell in children treated initially with calcium carbonate. All the children have been observed for a mean of 12.0 months (range 4 months to 3 1/2 years). Hypercalcemia occurred in seven children, usually when vitamin D therapy was initiated or the dose changed. Hypercalcemia resolved with adjustment of the vitamin D or calcium carbonate dose in all but one patient.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calcium carbonate is an effective phosphorus binder in children with chronic renal failure. 382 69

31P NMR signals from substrates and products of alkaline phosphatase have been adapted to measure the rates and product ratios for the hydrolysis and phosphotransferase reactions from pH 6 to 10. Below pH 8, glycerol is a poorer acceptor than H2O (glycerol phosphates:Pi = 0.5). Tris is a more effective acceptor below pH 8, showing a maximum acceptor efficiency at pH 8 (Tris phosphate:Pi = 2). Phosphotransferase efficiencies are in the order expected for the pKaS of the alcohol groups, Tris less than glycerol Cl, C3 less than glycerol C2. Tris and glycerol induce chemical shifts in 113Cd(II) present at the A site but not the B or C sites of the metal triad present at each active center of Cd(II)6 alkaline phosphatase, suggesting that the alcoxides of the acceptors coordinate the A site metal and become the nucleophiles attacking the phosphoseryl residue (E-P) in the second step of the mechanism. The interaction is through the oxygen of Tris. The transferase activity of the amino alcohol shows a bell-shaped pH dependency. Aliphatic alcohol acceptors show small increases in acceptor activity between pH 6 and 8, with 5-fold increases from pH 8 to 10 (at pH 10, glycerol phosphates:Pi = 2.5). 31P NMR inversion transfer has been used to measure the koff for Pi dissociation from the noncovalent enzyme complex (E . P). For the Zn(II)4 alkaline phosphatase koff is essentially pH independent at approximately 35 s-1. For Cd(II) or Mg(II) at the B site in place of Zn(II), koff less than or equal to 1 s-1 X Cl-ion, which appears to coordinate the A site metal ion, enhances koff, suggesting that both Cl- and HPO2-4 can coordinate the A site metal ion in a 5-coordinate intermediate. pH control of the alkaline phosphatase mechanism appears to reside in the stability of E-P and not the dissociation of E . P, compatible with the hypothesis that the activity-linked pKa is that of a H2O molecule coordinated to the A site metal, which in the hydroxide form becomes the nucleophile attacking the phosphoseryl group (E-P).
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PMID:Alkaline phosphatase. 31P NMR probes of the mechanism. 388 2

The use of cerium ions as a primary capture reagent in phosphatase histochemistry on the light and the electron microscopic level is a progress in the field of enzyme localization. Many influences of other captures (as of lead ions), e.g. enzyme inhibition, diffusion and other artefacts, are restricted when cerium-based methods are used. But the broader use of cerium is difficult, because cerium ions are at alkaline pH converted to the insoluble cerium hydroxide, which intensively precipitates in the incubation medium. This is an important disadvantage for a successful histochemical detection of alkaline phosphatase. The aim of this paper is to describe a new cerium-based method for the light microscopical detection of alkaline phosphatase, which is free from all these above mentioned problems. It is proposed a collidine buffer-sucrose containing medium, which holds cerium ions at pH = 9.0 in solution. The histochemical results of this method are excellent. The method is compared with a strontium based technique, the coupling azo dye technique for alkaline phosphatase as well as with in vitro and histochemical experiments with several chelator agents. The cerium-based collidine-sucrose technique is superior to all other procedures tested here and is recommended for a broader use.
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PMID:Light microscopical localization of enzymes by means of cerium-based methods. II. A new cerium-lead-technique for alkaline phosphatase. 393 56

1. Benzyl phosphonates were prepared and their potentialities as chromophoric reagents for the exploration of the substrate-binding site of Escherichia coli alkaline phosphatase were investigated. 4-Nitrobenzylphosphonate is a competitive inhibitor of the enzyme. 2-Hydroxy-5-nitrobenzylphosphonate changes its spectrum on binding to the enzyme. This spectral change is reversed when the phosphonate is displaced from the enzyme by substrate. 2. The kinetics of the reaction of 2-hydroxy-5-nitrophenylphosphonate were studied by the stopped-flow and the temperature-jump techniques. It was found that the combination of the phosphonate with the enzyme occurred in two successive and reversible steps: enzyme-phosphonate complex-formation followed by rearrangement of the complex. The spectral change is associated with the rearrangement. At pH8 in 1m-sodium chloride at 22 degrees the rate constant is 167sec.(-1) for the rearrangement of the initially formed binary complex and is 18sec.(-1) for the reverse process. 3. It has previously been proposed that the reactions of phosphatase with its substrates include a distinct step between enzyme-substrate combination and chemical catalysis. The rate constant involved could be predicted but not measured from experiments with substrates. The value for the rate constant measured from the rate of the enzyme-phosphonate rearrangement is in excellent agreement with the predicted value. A model for the reaction mechanism is proposed that includes a conformation change in response to phosphate ester binding before phosphate transfer from substrate to enzyme.
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PMID:A substate-induced conformation change in the reaction of alkaline phosphatase from Escherichia coli. 489 58

1. Radioactivity was incorporated into 5'-O-phosphoryladenylyl-(3'-5')-adenosine (pApA) on incubation with adenylate kinase and [gamma-(32)P]ATP. The corresponding triadenylate and tetra-adenylate reacted more slowly. 2. Only oligoadenylate with a terminal 5'-phosphate served as the substrate. 3. The product formed from pApA was shown to behave like 5'-O-pyrophosphoryladenylyl-(3'-5')-adenosine (ppApA) on hydrolysis with alkaline phosphatase, potassium hydroxide and hydrochloric acid. 4. The characteristics of the reaction indicated that it was catalysed by adenylate kinase, but the rate of phosphate transfer from ATP to pApA was about 0.01% of that in the typical reaction with AMP. 5. The reverse reaction between ADP and ppApA occurred readily, but no additional phosphorylation of ppApA (to give pppApA) could be demonstrated.
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PMID:The phosphorylation of 5'-oligoadenylic acids by adenylate kinase and adenosine triphosphate. 569 May 36

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the enzyme catalyzing the rate-limiting step in cholesterol biosynthesis, exists in one active (dephosphorylated) and one inactive (phosphorylated) form in liver microsomes obtained from several animal species. The present study was undertaken in order to determine a) whether the human enzyme also exists in active and inactive readily interconvertible forms; b) whether the large inter-individual variation in HMG-CoA reductase activity observed in normal man can be explained by variations in the activation state of the enzyme; and c) to characterize the reactivity of antibodies raised against rat liver HMG-CoA reductase with the intact human microsomal enzyme. HMG-CoA reductase activity, assayed in microsomes prepared in the presence of 50 mM NaF, was only 17 +/- 3% of the activity observed in microsomes prepared from the same liver in the absence of fluoride. Preincubation of microsomes prepared in NaF with alkaline phosphatase resulted in a tenfold increase of enzyme activity, while the activity of microsomes prepared without fluoride was increased also (by about 45%) with this treatment. On the other hand, the activated enzyme could be inactivated by incubation of microsomes with Mg-ATP. In eleven normal weight, normolipidemic gallstone patients, the HMG-CoA reductase activity determined in microsomes prepared without NaF ("standard procedure") reflected well both the "expressed" activity (in microsomes prepared with NaF) and the "total" (fully activated) enzyme activity; correlation coefficients were +0.80 and +0.84, respectively. Preincubation of human liver microsomes with rabbit antiserum against partially purified HMG-CoA reductase from rat liver resulted in a 72 +/- 6% inhibition of enzyme activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:3-hydroxy-3-methylglutaryl coenzyme A reductase in human liver microsomes: active and inactive forms and cross-reactivity with antibody against rat liver enzyme. 608 40

Fifteen children undergoing continuous ambulatory peritoneal dialysis for 0.3 to 2.4 years were evaluated longitudinally for renal osteodystrophy. Immunoreactive parathyroid hormone, 25-OHD, total and ionized calcium, inorganic phosphate, and alkaline phosphatase levels were measured regularly. Skeletal radiographic studies were performed at the onset and conclusion of CAPD and at six-month intervals during therapy. All children received 1,25(OH)2D3 and aluminum hydroxide, and nine received supplemental calcium. Plasma 25-OHD concentrations were normal to elevated, and calcium increased steadily to high normal levels despite a trend to persistent hyperphosphatemia. The increased calcium levels suppressed parathyroid hormone overactivity in only one patient. At the onset of CAPD, nine patients had hyperparathyroid bone disease seen radiographically, three of whom also had rachitic lesions. At the end of CAPD, the hyperparathyroid lesions had improved in four patients, completely resolved in three, and deteriorated in two. Rachitic lesions had completely healed in two patients and improved in the third. However, among the six children without radiographically evident lesions at onset of CAPD, hyperparathyroid bone lesions developed in two and rachitic lesions in two others during CAPD. Although CAPD and appropriate therapy benefited most patients with renal osteodystrophy, the benefits were not uniform, and bone lesions deteriorated in some.
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PMID:Renal osteodystrophy in children undergoing continuous ambulatory peritoneal dialysis. 663 99


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