Search results for " GEL"

Thin-layer chromatography of 2-methyl-4-chlorophenoxyacetic acid and its soil metabolites

1980

Abstract The thin-layer chromatography of 2-methyl-4-chlorophenoxyacetic acid, 4-chloro- o -cresol and 3-methyl-5-chlorocatechol and their pentafluorobenzyl derivatives has been studied on silica gel as adsorbent with 19 solvent systems. The best separation of the individual components occurred with toluene-benzene-acetic acid (2:2:1). Chloroform-diethyl ether-toluene (1:1:1) was suitable for the group separation of the pentafluorobenzyl derivatives.

Sputum metalloproteinase-9/tissue inhibitor of metalloproteinase-1 ratio correlates with airflow obstruction in asthma and chronic bronchitis

1998

Asthma and chronic bronchitis are inflammatory diseases with extracellular matrix (ECM) remodeling and collagen deposition. Collagen homeostasis is controlled by metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). We evaluated MMP and TIMP balance in induced sputum of 10 control, 31 untreated asthmatic, and 16 chronic bronchitic subjects. We first performed zymographic analysis to identify the profile of MMPs. Zymography revealed a similar MMPs profile in all populations studied and that MMP-9 was the major enzyme released. We then measured, using enzyme immunoassay, the concentrations of MMP-9 and of its inhibitor TIMP-1 and evaluated whether airflow limitation m…

Altered pore-forming properties of proteolytically nicked staphylococcal alpha-toxin

1993

Staphylococcal alpha-toxin is a single-chain polypeptide with a molecular weight of 34,000 that hexamerizes in lipid bilayers to form pores of 1-1.5 nm effective diameter in membranes. We demonstrate that limited proteolysis of purified alpha-toxin with proteinase K generates a hemolytically active product that yields one major protein band of 17-18 kDa in SDS-polyacrylamide gel electrophoresis. The 17-18-kDa protein band harbors two major fragments of similar size representing the N- and C-terminal halves, which remain associated with each other in non-denaturing buffers but dissociate in 6 M urea. Dissociation in urea leads to loss of hemolytic activity. In contrast, unnicked alpha-toxin …

“Primavera siciliana”: nota a Hdt. VII 162

2021

L'articolo propone una rilettura dell'epilogo del logos siciliano, incluso nel settimo libro delle Storie di Erodoto. L'episodio racconta la visita degli ambasciatori greci alla corte di Gelone, tiranno di Siracusa, che giunsero in Sicilia per chiedere il suo aiuto contro l'imminente attacco dei persiani. Un riesame del dialogo tra gli ambasciatori e il siracusano permette una reinterpretazione della frase finale con cui Gelone congeda gli ambasciatori greci, diversa da quella che si ritrova nei commenti ad Erodoto. The article offers a rereading of the epilogue of the Sicilian logos, included in the Seventh book of the Histories of Herodotus. The episode relates the visit of the Greek amba…

Application of a three-dimensional drawing procedure to the evaluation of series of protein samples after analysis by gel electrophoresis and other m…

1981

Hydrodynamic chromatography of macromolecules on 2 μm non-porous spherical silica gel packings

1989

Non-porous spherical 2μm silica gel particles have been tested as packing for hydrodynamic chromatography of macromolecules (HDC). Columns packed with these particles in 250×4.6mm i.d. columns can be operated very efficiently (e.g. a reduced plate height of about 2) when the detection cell is miniaturized. The packing is suitable for the separation of polystyrenes of Mw of 104–107 by hydrodynamic chromatography and the retention behaviour of polystyrenes agrees well with the known theoretical models. Preliminary results on the applicability of HDC for the separation of biopolymers are presented.

Sedimentation properties of chitosomal chitin synthetase from the wild-type strain and the 'slime' variant of Neurospora crassa.

1989

Marked differences in the pattern of sedimentation of cellular structures were observed after isopycnic centrifugation of crude cell-free preparations from the Neurospora crassa wall-less 'slime' variant and mycelial wild-type strain. Kinetic studies of particle sedimentation showed that the various types of subcellular components, as revealed by turbidity, UV absorption, polypeptide patterns, and chitin synthetase activity determinations, sediment independently of one another. An important feature was the finding that chitin synthetase from 'slime' peaked at a median specific gravity of 1.1201 +/- 0.0036, whereas that from wild-type strain sedimented at a higher buoyant density (specific g…

Baeyer—Villiger Oxidation in Supercritical CO2 with Potassium Peroxomonosulfate Supported on Acidic Silica Gel.

2006

Supercritical carbon dioxide (scCO2) is an efficient reaction medium to perform the Baeyer-Villiger oxidation with hydrated silica-supported potassium peroxomonosulfate (h-SiO2.KHSO5) under flow-through conditions. Hydration modulates the reactivity of the active surface by softening the acidity of the KHSO4 present in the supported reagent. The reaction in scCO2 is much more efficient than in n-hexane under similar conditions, which is attributed to better transport and solvating properties of the supercritical medium with regard to n-hexane.

Characterization of a T-cell-derived mast cell costimulatory activity (MCA) that acts synergistically with interleukin 3 and interleukin 4 on the gro…

1990

The proliferation of mucosal mast cells (MMC) depends on the presence of interleukin 3 (IL 3) and can be further enhanced by interleukin 4 (IL 4). The supernatant of a TH2 cell clone (ST2/K.9) stimulated by concanavalin A was found to contain a factor, provisionally termed mast cell costimulatory activity (MCA), that substantially enhances the proliferation of MMC promoted by a combination of IL 3 and IL 4. In comparison to other lymphokines MCA is rather resistant to tryptic digestion but is very sensitive to pH values lower than 6.0 and to organic solvents. Chromatographic fractionation of MCA revealed that activity is associated with protein(s) or glycoprotein(s) of 35 to 40 kDa. Partial…

Improved resolution power of electrophoretic fractionation of DNA using a voltage gradient up and down application

2004

The improved resolution power of electrophoretic fractionation of DNA in a wide range of molecular masses is demonstrated using an "up and down" application of voltage gradient gel electrophoresis (VGGE). This application also allows separation of different DNA fragments which are poorly fractionated in conventional electrophoresis.