Search results for "isoenzymes"
showing 10 items of 244 documents
Molecular phylogenetics and historical biogeography of the west-palearctic common toads (Bufo bufo species complex)
2012
In most pan-Eurasiatic species complexes, two phenomena have been traditionally considered key processes of their cladogenesis and biogeography. First, it is hypothesized that the origin and development of the Central Asian Deserts generated a biogeographic barrier that fragmented past continuous distributions in Eastern and Western domains. Second, Pleistocene glaciations have been proposed as the main process driving the regional diversification within each of these domains. The European common toad and its closest relatives provide an interesting opportunity to examine the relative contributions of these paleogeographic and paleoclimatic events to the phylogeny and biogeography of a wide…
Influence of inorganic pyrophosphate on the kinetics of muscle pyruvate kinase: a simple nonallosteric feedback model.
2002
Potassium pyrophosphate was used instead of ATP as a model ligand for magnesium cation for the study of effector influence on the kinetics of pyruvate kinase muscle isozyme M1. The pyruvate kinase activation by low concentration of pyrophosphate and inhibition by high concentration of pyrophosphate was considered to be the result of reversible reactions of magnesium cation with pyrophosphate, ADP, ATP, and PEP. The apparent Km and Vm or in some cases the pseudo-first order reaction rate constant (instead of Km and Vm) of pyruvate kinase at any given pyrophosphate concentration were analysed as a function of concentration of free magnesium cation and its complexes with all ligands present in…
Differential Enantioselectivity of Murine GlutathioneS-Transferase Isoenzymes in the Glutathione Conjugation ofTrans-3,4-dihydroxy-1,2-oxy- 1,2,3,4-t…
1998
Abstract The kinetics of the glutathione (GSH) conjugation of (+)- and (−)-enantiomers ofanti- as well assyn-3,4-dihydroxy-1,2-oxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene (B[c]PDE) catalyzed by murine GSHS-transferase (GST) isoenzymes has been investigated. Murine GSTs exhibited significant differences in their enantioselectivity toward B[c]PDE stereoisomers. For example, while pi class isoenzyme mGSTP1-1 was virtually inactive toward stereoisomers with 1Sconfiguration [(−)-syn-and (+)-anti-B[c]PDE], these stereoisomers were good substrates for alpha class isoenzyme mGSTA1-2. When GST activity was measured as a function of varying B[c]PDE concentration (10–320 μM) at a fixed saturating conce…
BDNF regulates spontaneous correlated activity at early developmental stages by increasing synaptogenesis and expression of the K+/Cl- co-transporter…
2003
Spontaneous neural activity is a basic property of the developing brain,which regulates key developmental processes, including migration, neural differentiation and formation and refinement of connections. The mechanisms regulating spontaneous activity are not known. By using transgenic embryos that overexpress BDNF under the control of the nestin promoter, we show here that BDNF controls the emergence and robustness of spontaneous activity in embryonic hippocampal slices. Further, BDNF dramatically increases spontaneous co-active network activity, which is believed to synchronize gene expression and synaptogenesis in vast numbers of neurons. In fact, BDNF raises the spontaneous activity of…
Co-regulation between cyclo-oxygenase-2 and inducible nitric oxide synthase expression in the time-course of murine inflammation.
2000
Many in vitro studies have used cell cultures to focus on the relationships between cyclo-oxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) isoforms. We have investigated the time-course of regulation and the role of COX-2 and iNOS in a model of experimental inflammation in mice, the air pouch injected with zymosan. This study demonstrates that there is an early acute phase (4 h) mediated mainly by eicosanoids, with high levels of prostaglandin E2 (PGE2) produced by cyclo-oxygenase-1. In addition, in the later phase (from 12 h) there is a participation of nitric oxide (NO) and PGE2 accompanied by co-induction of both iNOS and COX-2. These enzymes were detected in migrating leuk…
Effects of cyclooxygenase-1/cyclooxygenase-2 inhibition on leukocyte/endothelial cell interactions in the rat mesentery.
2002
Nonsteroidal anti-inflammatory drugs (NSAID) inhibit cyclooxygenase activity and cause gastrointestinal damage in part by promoting leukocyte accumulation in the mucosa. Our aim was to evaluate the effects of selective blockade of the isoenzymes cyclooxygenase-1 and cyclooxygenase-2 on leukocyte adhesion in vivo. Leukocyte/endothelial cell interactions were examined in rat mesenteric venules before and after treatment with indomethacin, SC-560 (5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethylpyrazole, cyclooxygenase-1 inhibitor), DFP (5,5-dimethyl-3-(2-propoxy)-4-(4-methanesulfonyl)-2(5H)-furanone, cyclooxygenase-2 inhibitor), or SC-560 plus DFP (20 mg/kg, i.v. each). Indomethacin i…
Stability of phospholipase D in primary astrocytes.
2002
Induction of expression and proteolytic breakdown of phospholipase D (PLD) isoforms in primary astrocyte cultures have been investigated. Astrocytes express both PLD1 and 2 and are dependent on PLD activity for cell proliferation [K. Kotter, J. Klein, J. Neurochem. 73 (1999) 2517]. Competitive RT-PCR analysis demonstrated a higher level of PLD1 mRNA than PLD2 mRNA (8.9 vs. 0.9amol/microg RNA, respectively). Treatment of astroglial cultures with the phorbol ester, 4beta-phorbol-12beta,13alpha-dibutyrate (0.1 microM), for 24-48h selectively induced PLD1b but not PLD1a or 2 expression as shown by PCR and Western blot; the effect was sensitive to Go 6976. In cells transiently permeabilized with…
Estrogens increase transcription of the human endothelial NO synthase gene: analysis of the transcription factors involved.
1998
Abstract —Estrogens have been found to reduce the incidence of cardiovascular disease that has been ascribed in part to an increased expression and/or activity of the vasoprotective endothelial NO synthase (NOS III). Some reports have shown that the level of expression of this constitutive enzyme can be upregulated by estrogens. The current study investigates the molecular mechanism of the NOS III upregulation in human endothelial EA.hy 926 cells. Incubation of EA.hy 926 cells with 17β-estradiol or the more stable 17α-ethinyl estradiol enhanced NOS III mRNA and protein expression up to 1.8-fold, without changing the stability of the NOS III mRNA. There was no enhancement of NOS III mRNA af…
Cadmium effects on p38/MAPK isoforms in MDA-MB231 breast cancer cells
2009
Emerging evidence seems to indicate that the heavy metal cadmium (Cd) is able to regulate gene expression, drastically affecting the pattern of transcriptional activity in normal and pathological eukaryotic cells, also affecting intracellular signalization events. Human p38 is a family of mitogen-activated protein kinases consisting of four isoforms (alpha, beta, gamma and delta) which mediate signal transduction cascades controlling several aspects of cell physiology. In this study we examined whether exposure of MDA-MB231 tumor cells from the human breast to Cd may exert some effect on p38 isoform expression and accumulation, as well as on p38 activation. Employing a combination of prolif…
Purification, isolation and characterization of a phosphoglycolate phosphatase isoenzyme from human erythrocytes.
1982
1. Preparation, purification and characterization of a phosphoglycolate phosphatase (PGP) isoenzyme from human erythrocytes was achieved by DEAE-Sepharose CL-6B chromatography and isoelectric focusing using carrier ampholytes, pH 4-6. 2. The isoenzyme has an isoelectric point of 5.00 +/- 0.05 and could be purified 33,000 fold to a specific activity of 32.7 U/mg of protein. It represents the PGP phenotype 1 consisting of a single isoenzyme. 3. The enzyme is composed of two subunits (mol. wt 35,000) which are identical and not connected by SS-bridges. 4. At 4 degrees C the isoenzyme is more stable in the pH range of 7-9 than at acid pH values. 5. Incubation at 30 and 40 degrees C for 4 hr doe…