ABSTRACT
An extracellular alkaline lipase from Pseudomonas aeruginosa mutant has been purified to homogeneity using acetone precipitation followed by anion exchange and gel filtration chromatography and resulted in 27-fold purification with 19.6% final recovery. SDS-PAGE study suggested that the purified lipase has an apparent molecular mass of 67 kDa. The optimum temperature and pH for the purified lipase were 45°C and 8.0, respectively. The enzyme showed considerable stability in pH range of 7.0-11.0 and temperature range 35-55 °C. The metal ions Ca2+, Mg2+ and Na+ tend to increase the enzyme activity, whereas, Fe2+ and Mn2+ ions resulted in discreet decrease in the activity. Divalent cations Ca+2 and Mg+2 seemed to protect the enzyme against thermal denaturation at high temperatures and in presence of Ca+2 (5 mM) the optimum temperature shifted from 45°C to 55°C. The purified lipase displayed significant stability in the presence of several hydrophilic and hydrophobic organic solvents (25%, v/v) up to 168 h. The pure enzyme preparation exhibited significant stability and compatibility with oxidizing agents and commercial detergents as it retained 40-70% of its original activities. The values of Km and Vmax for p-nitrophenyl palmitate (p-NPP) under optimal conditions were determined to be 2.0 mg.mL-1 and 5000 μg.mL-1.min-1, respectively.
Subject(s)
Lipase/metabolism , Pseudomonas aeruginosa/enzymology , Chemical Precipitation , Chromatography, Gel , Chromatography, Ion Exchange , Cations/metabolism , Enzyme Activators , Enzyme Stability , Enzyme Inhibitors/metabolism , Hydrogen-Ion Concentration , Kinetics , Lipase/chemistry , Lipase/isolation & purification , Metals/metabolism , Oxidants/metabolism , Pseudomonas aeruginosa/genetics , Solvents/metabolism , TemperatureABSTRACT
During membrane depolarization associated with skeletal excitation-contraction (EC) coupling, dihydropyridine receptor [DHPR, a L-type Ca2+ channel in the transverse (t)-tubule membrane] undergoes conformational changes that are transmitted to ryanodine receptor 1 [RyR1, an internal Ca2+-release channel in the sarcoplasmic reticulum (SR) membrane] causing Ca2+ release from the SR. Canonical-type transient receptor potential cation channel 3 (TRPC3), an extracellular Ca2+-entry channel in the t-tubule and plasma membrane, is required for full-gain of skeletal EC coupling. To examine additional role(s) for TRPC3 in skeletal muscle other than mediation of EC coupling, in the present study, we created a stable myoblast line with reduced TRPC3 expression and without alpha1SDHPR (MDG/TRPC3 KD myoblast) by knock-down of TRPC3 in alpha1SDHPR-null muscular dysgenic (MDG) myoblasts using retrovirus-delivered small interference RNAs in order to eliminate any DHPR-associated EC coupling-related events. Unlike wild-type or alpha1SDHPR-null MDG myoblasts, MDG/TRPC3 KD myoblasts exhibited dramatic changes in cellular morphology (e.g., unusual expansion of both cell volume and the plasma membrane, and multi-nuclei) and failed to differentiate into myotubes possibly due to increased Ca2+ content in the SR. These results suggest that TRPC3 plays an important role in the maintenance of skeletal muscle myoblasts and myotubes.
Subject(s)
Animals , Mice , Calcium/metabolism , Calcium Channels/metabolism , Calcium Channels, L-Type/genetics , Cations/metabolism , Cell Differentiation , Cell Proliferation , Cells, Cultured , Excitation Contraction Coupling , Gene Knockdown Techniques , Membrane Potentials , Muscle Fibers, Skeletal/metabolism , Muscle Proteins/metabolism , Myoblasts, Skeletal/metabolism , Ryanodine Receptor Calcium Release Channel/metabolism , Sarcoplasmic Reticulum/physiology , Synaptophysin/metabolism , TRPC Cation Channels/genetics , Transient Receptor Potential Channels/metabolismABSTRACT
A pot experiment was conducted with the objectives to assess the adaptation potential of fennel crop grown at 10, 20, 25, 35 and 40 ESP (exchangeable sodium percentage) levels. Results showed that the rate of seed germination, plant growth including branching pattern, umbels per plant and 1000 test seed weight were adversely affected by sodic soils. Assuming that fifty percent reduction in seed yield and Na+/K+ ratio in leaf tissue as an index of alkali tolerance revealed that fennel was tolerant up to 25 ESP. The cell sap pH and EC reflected optimum osmoticum maintenance to withstand sodicity stress at this level and beyond this leaf water potential decreased (negatively) more to impede water uptake.
Subject(s)
Biomass , Cations/metabolism , Dose-Response Relationship, Drug , Foeniculum/drug effects , Germination/drug effects , Hydrogen-Ion Concentration , Seeds/drug effects , Sodium/toxicity , Soil/analysis , Water/metabolism , Water-Electrolyte Balance/drug effectsABSTRACT
En las células de mamíferos, los aminoácidos son captados por diferentes sistemas de transporte presentes en la membrana plasmática. Los sistemas de transporte originalmente se caracterizaron a través de estudios cinéticos y de competencias. Sin embargo, el asignamiento de algunos aminoácidos a un sistema de transporte específico había sido difícil. Con los avances en biología molecular ha sido posible identificar a las proteínas de los transportadores para aminoácidos específicos. En esta revisión se describen los sintomas de transporte para aminoácidos aniónicos y catiónicos que se han reportado a nivel molecular. Los aminoácidos aniónicos se movilizan principalmente a través de los sistemas XAG- y Xc-, los cuales son de particular relevancia en la inactivación de la transmisión nerviosa glutamatérgica en el cerebro y en la síntesis de glutation, respectivamente. Se han descrito cuatro isoformas cerebrales del sistema XAG- pertenecientes a la familia de transportadores de aminoácidos dependientes de Na+. Los sistemas de transporte para los aminoácidos catiónicos también reconocen sustratos zwitteriónicos, y los más estudiados son el y+, y+L, bº + y Bº + La regulación de la entrada de aminoácidos catiónicos tales como la arginina, lisina, y ornitina es importante en la biosíntesis de oxido nítrico, creatina, carnitina y poliaminas. La cisteinuría es un defecto hereditario asociado al sistema bº +
Subject(s)
Humans , Animals , Mice , Rats , Glutamic Acid/metabolism , Amino Acids/metabolism , Anions/metabolism , ATP-Binding Cassette Transporters/metabolism , Biological Transport , Cations/metabolism , Cerebrum/metabolism , Cystinuria/metabolism , Intestinal Mucosa/metabolism , Metabolism, Inborn Errors , Models, Molecular , Membrane Proteins/metabolismABSTRACT
This review describes and analyzes the evidence from studies using noncompetitive inhibitors of the nicotinic acetylcholine receptor that the receptor's ion channel is formed by the second transmembrane segment of all five receptor subunits. Inconsistencies in this generally accepted model are also presented and discussed
Subject(s)
Animals , Cholinergic Antagonists/pharmacology , Ion Channels/drug effects , Receptors, Cholinergic/antagonists & inhibitors , Amino Acid Sequence , Ion Channel Gating/drug effects , Binding Sites , Ion Channels/metabolism , Cations/metabolism , Models, Chemical , Molecular Sequence Data , Neurotoxins/pharmacology , Protein Conformation , Receptors, Cholinergic/chemistry , Receptors, Cholinergic/metabolismABSTRACT
Lens transparency is a function of regular cell shape, regular cell volume, minimal extracellular space, and minimal scatter elements. The cellular structure and molecular structure of the lens is reviewed. The importance of the cytoarchitecture especially the sutures, is discussed. The high cholesterol: phospholipid ratio of the lens fiber cell membranes is related to the functions of low permeability, low fluidity, and mechanical stability. Also reviewed are the contributions of the lens crystallins to lens clarity and to lens refractive index. The importance of intracellular and extracellular cation and water concentrations are reviewed. Finally the effects of systemic diseases, oxidation, and light on lens clarity are discussed relative to changes in lens fiber cell cation concentrations
Subject(s)
Animals , Humans , Cataract/etiology , Adenosine Triphosphate/metabolism , Cataract/metabolism , Cataract/pathology , Cations/metabolism , Lens, Crystalline/metabolism , Lens, Crystalline/ultrastructure , Light/adverse effects , Oxidants/metabolismSubject(s)
Mice , Rats , Animals , Male , Biliary Tract , Cations/metabolism , Diagnostic Imaging/metabolism , Sodium Pertechnetate Tc 99m , Cell Membrane/metabolism , Cells, Cultured , Cells, Cultured/metabolism , Liver , Liver/cytology , Liver/metabolism , Ouabain/pharmacokinetics , Proteins/metabolism , Sodium Pertechnetate Tc 99m/antagonists & inhibitorsABSTRACT
O magnésio (Mg) desempenha papel expressivo em muitos processos metabólicos e os distúrbios do metabolismo deste cation interferem na pressäo arterial, na mortalidade do infarto agudo do miocárdio, em arritmias ventriculares e na contratilidade miocárdica; na insuficiência cardiaca há diminuiçäo do Mg intracelular que pode näo se refletir no Mg circulante. O propósito deste trabalho foi o estudo do Mg linfocitário em 3 cardiopatas internados na Clínica Geral do HCFMUSP. Separamos linfócitos do sangue periférico usando gradiente de densidade em meio Ficoll 400-metrizoato de sódio; as células foram lisadas por congelaçäo permitindo a dosagem da concentraçäo do Mg celular em espectrômetro de absorçäo atômica. Nos 3 casos o comportamento do Mg linfocitário correlacionou-se com o estado geral e em 1 caso houve correlaçäo da concentraçäo do catión com variáveis nutricionais; a dosagem sistemática do Mg linfocitário poderá esclarecer o papel deste cation na insuficiência cardíaca e talvez na relaçäo insuficiência cardíaca-desnutriçäo