Production and properties of inulinase from Aspergillus niger

Summary A thermostable inulinase was identified in a strain of A. niger. The highest activity was observed at 50 °C (50 Lml^–1) and 77% and 34% of this was retained at 60° and 65°C, respectively. pH stability, the effect of thermal stabilizers such as Propylene glycol (10%) and Sorbitol (10%) and effects of different cations were investigated. It was found that the activity was completely inhibited by Ag⁺ and Hg²⁺, while Na⁺ had an activator effect.     

Melatonin ameliorates cardiac remodelling in fructose-induced metabolic syndrome rat model by using genes encoding cardiac potassium ion channels

Molecular Biology Reports - Metabolic syndrome comprises a group of disorders, including cardiac abnormalities. Ventricular arrhythmias observed in metabolic syndrome are due to the impaired...     

The role of aromatic residues in the hydrophobic core of the villin headpiece subdomain

Small autonomously folding proteins are of interest as model systems to study protein folding, as the same molecule can be used for both experimental and computational approaches. The question remains as to how well these minimized peptide model systems represent larger native proteins. For example, is the core of a minimized protein tolerant to mutation like larger proteins are? Also, do minimized proteins use special strategies for specifying and stabilizing their folded structure? Here we examine these questions in the 35‐residue autonomously folding villin headpiece subdomain (VHP subdomain). Specifically, we focus on a cluster of three conserved phenylalanine (F) residues F47, F51, and F58, that form most of the hydrophobic core. These three residues are oriented such that they may provide stabilizing aromatic–aromatic interactions that could be critical for specifying the fold. Circular dichroism and 1D‐NMR spectroscopy show that point mutations that individually replace any of these three residues with leucine were destabilized, but retained the native VHP subdomain fold. In pair‐wise replacements, the double mutant that retains F58 can adopt the native fold, while the two double mutants that lack F58 cannot. The folding of the double mutant that retains F58 demonstrates that aromatic–aromatic interactions within the aromatic cluster are not essential for specifying the VHP subdomain fold. The ability of the VHP subdomain to tolerate mutations within its hydrophobic core indicates that the information specifying the three dimensional structure is distributed throughout the sequence, as observed in larger proteins. Thus, the VHP subdomain is a legitimate model for larger, native proteins.     

Inhibition of hydrogen uptake in <Emphasis Type="Italic">Escherichia coli</Emphasis> by expressing the hydrogenase from the cyanobacterium <Emphasis Type="Italic">Synechocystis</Emphasis>sp. PCC 6803

Background  

Molecular hydrogen is an environmentally-clean fuel and the reversible (bi-directional) hydrogenase of the cyanobacterium Synechocystis sp. PCC 6803 as well as the native Escherichia coli hydrogenase 3 hold great promise for hydrogen generation. These enzymes perform the simple reaction 2H⁺ + 2e^- ↔ H₂ (g).     

Chemotaxis of Pseudomonas stutzeri OX1 and Burkholderia cepacia G4 toward chlorinated ethenes

The chemotactic responses of Pseudomonas putida F1, Burkholderia cepacia G4, and Pseudomonas stutzeri OX1 were investigated toward toluene, trichloroethylene (TCE), tetrachloroethylene (PCE), cis-1,2-dichloroethylene (cis-DCE), trans-1,2-dichloroethylene (trans-DCE), 1,1-dichloroethylene (1,1-DCE), and vinyl chloride (VC). P. stutzeri OX1 and P. putida F1 were chemotactic toward toluene, PCE, TCE, all DCEs, and VC. B. cepacia G4 was chemotactic toward toluene, PCE, TCE, cis-DCE, 1,1-DCE, and VC. Chemotaxis of P. stutzeri OX1 grown on o-xylene vapors was much stronger than when grown on o-cresol vapors toward some chlorinated ethenes. Expression of toluene-o-xylene monooxygenase (ToMO) from touABCDEF appears to be required for positive chemotaxis attraction, and the attraction is stronger with the touR (ToMO regulatory) gene.     

Alpha-subunit positions methionine 180 and glutamate 214 of Pseudomonas stutzeri OX1 toluene-o-xylene monooxygenase influence catalysis

Alpha-subunit position M180 of toluene-o-xylene monooxygenase influences the regiospecific oxidation of aromatics (e.g., from o-cresol, M180H forms 3-methylcatechol, methylhydroquinone, and 4-methylresorcinol, whereas the wild type forms only 3-methylcatechol). Position E214 influences the rate of reaction (e.g., E214G increases p-nitrophenol oxidation 15-fold) by controlling substrate entrance and product efflux as a gate residue.     

The dual-function disabled-1 PTB domain exhibits site independence in binding phosphoinositide and peptide ligands

While typical intracellular protein modules have only one ligand-binding site, there are rare examples of single modules that bind two different ligands at distinct binding sites. Here we present a detailed mutational and energetic analysis of one such domain, the phosphotyrosine binding (PTB) domain of Disabled-1 (Dab1), which binds to both peptide and phosphoinositide (PI) ligands simultaneously at structurally distinct binding sites. Through the techniques of isothermal titration calorimetry (ITC), analysis of Dab1 PTB domain mutants, and nuclear magnetic resonance (NMR), we have evaluated the characteristics of binding of the Dab1 PTB domain to various peptide and PI ligands. These studies reveal that the presence of saturating concentrations of one ligand has little effect on the binding constant for a second ligand at the other site. In addition, proteins with single-point mutations in the peptide-binding site retain native affinity for PI ligands, while proteins with mutations that prevent PI binding retain native affinity for peptide. NMR titrations show that the final structure of the ternary complex is the same independent of the order of addition of the two ligands. Together, these studies show that binding of peptide and PI ligands is energetically independent and noncooperative.     

Clinical and laboratory aspects of a trichinellosis outbreak in Izmir, Turkey

Epidemiological, clinical and laboratory data were collected during an outbreak of trichinellosis, which occurred in Izmir, Turkey, between January and March 2004. The source of the infection was raw meatballs made with a mixture of uncooked beef and pork. Of 474 persons who were admitted at the Ataturk Training and Research Hospital during this period with a history of raw meatball consumption, the diagnosis of trichinellosis was confirmed for 154 (32.5%, 87 males and 67 females; mean age 31 years, range 6-67 years). Among persons with a confirmed diagnosis, 79% had myalgia, 77% weakness and malaise, 63% arthralgia, 40% jaw pain, 68% fever, 63% periorbital and/or facial oedema, 49% oedema at the trunk and limb, 42% abdominal pain, 40% nausea and vomiting, 28% diarrhoea, 23% subconjunctival haemorrhage, 25% macular or petechial rash, 4% subungual haemorrhage, 15% cardiac complaints and 0.2% neurological complaints. Nine patients (5.8%) were hospitalised due to severe myalgia (n = 2), high fever (n = 3), neurological manifestations (n = 1), thrombophlebitis (n = 2) and palmar erythema (n = 1). Eosinophilia was present in 88% of the confirmed cases at the admission. Elevated levels of serum creatine phosphokinase, lactic dehydrogenase and aspartate aminotransferase were detected in 72%, 70% and 16% of the confirmed cases, respectively. The seroconversion occurred in most of the infected people between the 4th and 6th weeks after the infection. All of the confirmed cases were treated with mebendazole. People with severe symptoms were treated also with prednisolone (60 mg/day for three days) and those with a moderately severe clinical pattern received a non-steroid anti-inflammatory drug (naproxen sodium, 550 mg/day). All confirmed cases recovered without any clinical sequela.     

Ultrastructural aspects and programmed cell death in the tapetal cells of Lathyrus undulatus Boiss

Programmed cell death (PCD) in the tapetum of Lathyrus undulatus L. was analyzed based on light, fluorescence and electron microscopy to characterize its spatial and temporal occurrence. Development and processes of PCD in secretory tapetal cells of Lathyrus undulatus L. were correlated with the sporogenous cells and pollen grains. At early stages of development the tapetal cells appeared similar to pollen mother cells, structurally. Concurrent with meiosis, tapetum expanded both tangentially and radially as vacuoles increased in size. Tapetal cells most fully developed at young microspore stage. However, tapetum underwent substantial changes in cell organization including nucleus morphology monitored by DAPI. The TUNEL staining confirmed the occurrence of intra-nucleosomal DNA cleavage. In addition to nuclear degeneration which is the first hallmark of PCD other diagnostic features were observed at vacuolated microspore stage intensely; such as chromatin condensation at the periphery of the nucleus, nuclear membrane degeneration, chromatin release to the cytoplasm, vacuole collapse according to tonoplast rupture, shrinkage of the cytoplasm, the increase and enlargement of the endoplasmic reticulum cisternae and disruption of the plasma membrane. After vacuole collapse due to possible release of hydrolytic enzymes the cell components degraded. Tapetal cells completely degenerated at bicellular pollen stage.