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)

A rapid, picomole-scale method is described to locate phosphorylation sites in phosphoproteins by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) combined with enzymatic modification of the analyte. There are three steps to locate phosphorylation sites in a phosphoprotein: (i) degradation of the phosphoprotein into small peptides by specific enzymatic or chemical reactions; (ii) identification of the phosphopeptides by -80 (or multiples of -80)-Da mass shifts in the mass spectra after dephosphorylation with alkaline phosphatase; (iii) location of the phosphorylation sites by mass mapping. As the size of the protein increases, it is advantageous to fractionate the mixture by HPLC and analyze each fraction by MALDI-TOF-MS. To perform mass mapping, the primary structure of the protein must be known. Bovine beta-casein was analyzed by this method. The conclusions about the specific phosphorylation sites of bovine beta-casein from our data coincide with previously reported results. From calculations, it is found that a mass spectrometer with 0.1% mass accuracy is sufficient, for mass mapping, to identify completely or partially digested tryptic peptides in the mass range of 100-8000 Da from bovine beta-casein (MW 23,983).
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PMID:An approach to locate phosphorylation sites in a phosphoprotein: mass mapping by combining specific enzymatic degradation with matrix-assisted laser desorption/ionization mass spectrometry. 805 60

The N-linked glycans assembled in Pichia pastoris on the recombinant kringle 2 domain of human tissue-type plasminogen activator (r-[K2tPA]) are composed of approx. 80% neutral and 20% charged species. After peptide:N4-(N-acetyl-beta-glucosaminyl)asparaginyl amidase-catalysed liberation of the oligosaccharides from the purified glycopeptide, the glycan mixture was resolved by HPLC on amino-silica-based resin. Oligosaccharide mapping of the resulting mixture by HPLC, gel filtration and time-of-flight matrix-assisted laser-desorption-ionization-with-delayed-extraction mass spectrometry (TOF-MALDI DE-MS) revealed that > 90% of the charged species consisted of a series of oligosaccharides possessing molecular masses that were consistent with a range of saccharides comprising phospho-Man10GlcNAc2-phospho-Man14GlcNAc2, with phospho-Man11GlcNAc2 representing the major species. The remaining material in the charged fraction contained identifiable phosphorylated glycans that were one or two mannose units shorter, and one to four mannose units longer, than those present in the above range of oligosaccharides. Treatment of the native charged glycan pool with alkaline phosphatase did not result in molecular-size alterations, showing that phosphomonoesters are not present. Mild acid hydrolysis of the glycans led to a decrease in the size of all charged glycans by one mannose residue, providing phospho-Man9GlcNAc2-phospho-Man13GlcNAc2. Following this procedure, treatment with alkaline phosphatase resulted in size decreases that were equivalent to the loss of one phosphate group from each glycan. This demonstrates that all charged glycans isolated contained phosphate in phosphodiester bonds to two mannose units. The present study shows that P. pastoris cells possess the capability of assembling phosphorylated glycans having the phosphate moiety present in phosphodiester linkages with two mannose units. These saccharides, like the neutral oligosaccharides, contain considerably smaller amounts of mannose than glycans present in other strains of yeast.
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PMID:Characterization of the acidic oligosaccharides assembled on the Pichia pastoris-expressed recombinant kringle 2 domain of human tissue-type plasminogen activator. 935 3

Placental alkaline phosphatase (PLAP) that had been isolated from human placenta was further purified using subsequent ion-exchange chromatography (IEC), affinity chromatography (AC) and centrifugal membrane concentration (CMC). During the process, the PLAP samples from the different stages of purification were characterized regarding purity and activity. This was accomplished by combining Lowry analysis, enzymatic activity assay, capillary zone electrophoresis (CZE), capillary gel electrophoresis (CGE) and matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF-MS). The sample obtained after IEC had a rather low specific activity (6.8 U/mg) and appeared to contain several major contaminants, among which was human serum albumin (HSA). AC followed by CMC yielded PLAP with a specific activity of 128 U/mg. The purity and identity of the protein was indicated by MALDI-TOF-MS yielding a spectrum with one major peak at m/z 58,101. Interestingly, CZE of the pure PLAP revealed a cluster of peaks, which probably reflects the presence of various glycoforms and/or oligomers. The same analytical approach was used to characterize commercially available PLAP. This sample showed a moderate specific activity (15 U/mg) and appeared to be highly impure containing various other proteins.
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PMID:Characterization of human placental alkaline phosphatase by activity and protein assays, capillary electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. 1139 19

Prostate cancer cells metastasize to bone causing a predominantly osteosclerotic response. It has been shown that cells from the human prostate cancer cell line PC3 secrete factors that influence the behavior of osteoblast-like cells. Some of these factors with mitogenic activity have been found to be proteins with molecular weights between 20 and 30 kDa, but the identity of the osteoblastic mitogenic factor or factors produced by prostate cancer cells is still unknown. Therefore, the aim of this study was to characterize the protein profile of conditioned medium (CM) from PC3 cells in the molecular weight range from 5 to 30 kDa using proteome analysis. A protein profile of the CM from PC3 cells was performed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Thirty protein spots with molecular weights ranging from 5 to 30 kDa were analyzed by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). One of these spots was identified as galectin-1. We examined whether PC3 CM, recombinant galectin-1 alone, or combined with insulin-like growth factor-I (IGF-I) had any effects on the proliferation or differentiation of human bone marrow stromal (hBMS) cells. Furthermore, we tested whether adhesion of PC3 cells to plastic, laminin, fibronectin, and collagen type I was influenced by lactose, which inhibits galectin-1. Galectin-1 (1000 ng/ml) inhibited the proliferation of hBMS cells up to 70 +/- 12% (treated/control) of control in contrast to PC3 CM, which induced hBMS cell proliferation by 3-fold. This effect was abolished by IGF-I. PC3 CM and galectin-1 in concentrations of 10 and 1000 ng/ml increased the alkaline phosphatase (ALP) activity of hBMS cells up to 175 +/- 27%, 137 +/- 8%, and 131 +/- 11%, respectively, compared with ALP activity of untreated cells, and inhibited the secretion of osteocalcin (OC) up to 81 +/- 3%, 93 +/- 1%, and 58 +/- 2%, respectively, compared with OC secretion of untreated cells. These effects were affected by IGF-I. Lactose inhibited adhesion of PC3 cells to plastic, fibronectin, laminin, and collagen type I up to 58 +/- 4%, 30 +/- 12, 72 +/- 9%, and 86 +/- 4%. In conclusion, galectin-1 modulated osteoblastic proliferation and differentiation. These effects were affected by IGF-I. Thus, galectin-1 is likely be involved in the osteoblastic response, caused by prostate cancer cells metastasizing into bone, by affecting the matrix mineralization.
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PMID:A proteome study of secreted prostatic factors affecting osteoblastic activity: galectin-1 is involved in differentiation of human bone marrow stromal cells. 1256 96

Prostate cancer cells metastasise to bone causing a predominantly osteosclerotic response. It has previously been shown that PC3 cells secrete factors which stimulate the mitogenic activity of human bone marrow stromal (hBMS) cells. Some of these mitogens have been found to be proteins with a molecular weight between 20 and 30 kDa. Even though a number of investigations have been performed to identify the osteoblastic mitogenic factor or factors produced by prostate cancer cells, it is still unknown what causes the mitogenic activation of osteoblasts. Therefore, the aim of this study was to characterise the protein profile of conditioned medium (CM) from PC3 cells in the molecular weight range of 5-30 kDa using proteome analysis. A protein profile of the CM from PC3 cells was performed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Thirty protein spots with molecular weights ranging from 5 to 30 kDa were analysed by matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF MS). One of these spots was identified as cyclophilin A. We examined whether cyclophilin A alone or in combination with insulin-like growth factor-I (IGF-I) had any effects on the proliferation or differentiation of hBMS cells. Cyclophilin A at 1, 10, and 100 nM and cyclophilin A at 10 nM combined with 10 ng/ml IGF decreased the proliferation of hBMS cells up to 49+/-30, 38+/-29, 50+/-8 and 60+/-16%, respectively [mean (treated/control)+/-standard error of the means (SEM)] of control. IGF-I did not significantly affect these decreases. Cyclophilin A alone or in combination with IGF-I did not have any effect on differentiation (assessed by measuring the activity of alkaline phosphatase (ALP)). In conclusion, these results suggest cyclophilin A is not involved in the osteosclerotic effects seen when prostate cancer metastasises to bone.
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PMID:A proteome study of secreted prostatic factors affecting osteoblastic activity: identification and characterisation of cyclophilin A. 1270 69

Protein phosphorylation is the most important reversible post-translational modification in cells. Analysis of phosphorylated proteins and identification of their phosphorylation sites is helpful for understanding their biological functions. MALDI-TOF-MS and ESI-Q-TOF-MS play important roles in protein phosphorylation analysis. In this work, immobilized metal affinity chromatography (IMAC) was used to selectively enrich phosphopeptides from protein digest mixtures, and treatment of phosphopeptides with alkaline phosphatase was used to confirm the phosphorylation. Finally, the phosphorylation sites were determined by tandem mass spectrometry analysis and database searching.
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PMID:[Analysis of protein phosphorylation by combination of IMAC, phosphatase with biological mass spectrometry]. 1276 8

We describe a reproducible protocol to explore for the first time the phosphoproteome of a seedless plant, the moss Physcomitrella patens. Following tryptic digestion of a total protein extract, phosphorylated peptides were isolated using the combination of C18 reverse-phase chromatography (RP-C18), immobilized Fe(3+) metal affinity chromatography (IMAC), capillary zone electrophoresis (CZE), liquid chromatography-tandem mass spectrometry (LC-MS/MS) and matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) analysis. The total protein extracts were first prepared as usually made for plant two-dimensional gel electrophoresis, the tryptic digest was desalted and concentrated by reverse phase chromatography, and from this mixture the phosphorylated peptides were captured by IMAC. Subsequently, the complex phosphopeptide mixture was separated into ten fractions by RP-C18-HPLC and each analyzed by CZE. This permitted the detection of 253 distinct phosphopeptides. These were identified by nano-LC-MS/MS and MALDI-TOF-MS analysis in conjunction with alkaline phosphatase treatment to remove covalently bound phosphate to specifically identify the phosphopeptides. Among others, several kinases and a transcription factor were identified. This protocol will be taken as a basis to unravel early events in plant signal transduction known to occur via rapid phosphorylation/dephosphorylation of proteins.
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PMID:An efficient protocol for the identification of protein phosphorylation in a seedless plant, sensitive enough to detect members of signalling cascades. 1509 59

The activity-stability-structure relationship of the cold-active alkaline phosphatase from Red Arctic shrimp, Pandalus borealis (SAP) was studied by chemically modifying aliphatic (C-H) or amino (NH2) groups using benzophenone tetracarboxylic derivatives in either a light (UV-A) or dark reaction. The response of the cold-adapted enzyme was compared to a similarly modified calf alkaline phosphatase (CAP). MALDI-TOF-MS was used to determine the extent and nature of the modifications in both SAP and CAP. On average 2 to 4 amino acid residues were linked to a BP-modifier, with up to 18 to 21 amino acids modified in a smaller portion of the material. The effect of the modifications on kinetic and thermodynamic properties varied with the enzyme and type of modification. The aliphatic-group modified SAP demonstrated typical characteristics of a mesophilic enzyme, consistent with an activity-stability trade-off where gain in thermostability was attained at the expense of decreased activity. In contrast, the activity of the amino-group modified SAP attained an even more psychrophilic character with respect to its kinetic (increase in kcat and Km) and thermodynamic (reduction in deltaH#) properties. Interestingly, the amino-group modified SAP also acquired higher thermostability, thus demonstrating that both activity and stability can be simultaneously enhanced using chemical modification. The study demonstrates the applicability of benzophenone chemical modification for improving the thermal properties of enzymes from psychrophiles and mesophiles.
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PMID:Improved activity and stability of alkaline phosphatases from psychrophilic and mesophilic organisms by chemically modifying aliphatic or amino groups using tetracarboxy-benzophenone derivatives. 1555 81

An anti-cancer peptide was purified from the Mercenaria (Meretrix meretrix Linnaeus) by the method of chromatography on Sephadex G-25 and FPLC, and its molecular weight was determined to be 3147 Da by the way of MALDI-TOF mass spectrum. The effects of this peptide on human gastric gland carcinoma cells (BGC-823) and their cytoskeletal morphology were investigated. The results showed that the peptide could inhibit the proliferation of BGC-823 cells and obviously destroy the skeletal structures of the cells. When the concentration of the peptide reached 4.0 microg/ml, the inhibition percentage of the cell growth was about 60%. The effects of this anticancer peptide on the activities of superoxide dismutase (SOD), alkaline phosphatase (ALP) and tyrosinase were studied. The results showed that the peptide activated ALP and SOD, but inhibit the tyrosinase activity. When the concentration of the peptide reached to 0.5 microg/ml, the relative activities of SOD, ALP and tyrosinase were determined to be 188.5%, 122.0% and 27.5%, respectively.
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PMID:Inhibitory effects of anticancer peptide from Mercenaria on the BGC-823 cells and several enzymes. 1571 Apr 11

We generated a series of adherent gene-amplified CHO clones expressing human secreted alkaline phosphatase (SEAP) as a model for heterologous protein production. Clones demonstrate a 26- to 52-fold increase in productivity compared to controls after dhfr/methotrexate-mediated gene amplification and clone selection. SEAP is stably expressed in these clones over at least a 6-week period without significant productivity loss. Two-dimensional protein electrophoresis identified 21 proteins that exhibited altered expression in clones of increasing SEAP productivity. Based on MALDI TOF/TOF mass spectrometry of relevant protein spots, changes in translation, energy pathways, chaperones, regulatory proteins, and cytoskeletal proteins were observed, including a 4-fold expression increase in actin capping protein. We hypothesized that an alteration of the actin cytoskeleton using cytochalasin D as a mimic for actin-capping protein could have a beneficial effect on heterologous protein secretion. Treatment with 0.5 mug/mL cytochalasin D increased SEAP productivity 2- to 3-fold compared to an amplified control which resulted in an increase in productivity from 52- to 150-fold compared to a nonamplified parent.
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PMID:Cytochalasin D can improve heterologous protein productivity in adherent Chinese hamster ovary cells. 1577 46


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