Investigation of the unit operations involved in the continuous flow isolation of β-galactosidase from Escherichia coli

A 1000 liter fermentor has been used to produce a continuous feed of Escherichia coli containing a high level of β-galactosidase. We have investigated the individual unit operations for the isolation of the enzyme: cell disruption, nucleic acid removal, protein precipitation, and solid–liquid separation after each stage. Using the information obtained we have been able to operate a semicontinuous process which when fully continuous would yield 100 g protein/hr, comprising 23% β-galactosidase.     

The kinetics of β-galactosidase attached to porous cellulose sheets

The properties of β-galactosidase attached to cellulose and DEAE-cellulose sheets arc described. Those insoluble enzyme derivatives obey the Michael-Menten relationship but, the measured kinetic parameters are very dependent on the flow conditions. The results of long-term stability tests are given.     

Stirred Tank Two-Liquid Phase Biocatalytic Reactor Studies: Kinetics, Evaluation and Modelling of Substrate Mass Transfer

Kinetic measurements of the benzyl acetate hydrolysis by pig liver esterase in a two-liquid phase stirred tank reactor were made at a variety of aqueous phase enzyme concentrations and stirrer speeds. All experiments were performed in an inverted liquid-liquid system at a high phase ratio. The results were explained in terms of the aqueous phase bulk reaction model developed from previous Lewis cell studies. An algorithm is presented for the indirect measurement of the substrate mass transfer coefficient and consequently a model was developed to predict reaction rates. While the model describes the kinetics effectively, and could therefore be used to predict reactor behaviour, no difference was observed between kinetic measurements made at a stirrer speed of 750 and 1000 rpm.     

The European searchable tumour line database

The European Searchable Tumour line Database (ESTDAB) () is a freely available and fully searchable database of melanoma-derived cell lines, which have been characterised for over 250 immunologically relevant markers by a consortium of European scientists. The database is linked to a cell bank, which can provide melanoma cell lines to non-profit investigators for a nominal handling charge. All cells are fully HLA typed at the genomic and surface expression levels. The expression of a number of surface antigens, apoptotic markers, tumour-associated antigens and extracellular matrix proteins has also been determined. Cytokine secretion has been tested and polymorphisms in cytokine genes have been identified. Glycans at the cell surface were identified and glycosyltransferase activity quantified. Cell lines with a particular constellation of these parameters can be sought online via the ESTDAB interface, which is included as part of the Immuno-Polymorphism Database (IPD) section of the European Bioinformatics Institute’s (EBI) website. This paper is a focussed research review from the meeting which took place on the 28th–29th May 2008 in Nottingham, UK, celebrating the contribution of Prof. I.A. “Tony” Dodi (29.1.2008) to the EU project “Network for the identification and validation of antigens and biomarkers in cancer and their application in clinical tumour immunology (ENACT).”     

Affinity Chromatography of 15-Hyoroxyprostaglandin Dehydrogenase from Dog Lung

A 15-hydroxyprostaglandin dehydrogenase has been purified from dog lung by NAD⁺-CH-Sepharose 4B affinity chromatography. The molecular weight of the enzyme determined by gel filtration is 46, 500. The biochemical properties of the dog lung enzyme are similar to that isolated from other sources.     

Slow sodium-free contractures in the frog heart mediated by the sodium-calcium exchange

1. Sodium-free contractures were studied in myocardial strips from R. pipiens when extracellular sodium (Na+o) was replaced by choline chloride and extracellular free calcium (Ca2+o) was defined with EGTA-buffer. 2. Resting membrane potentials (RMP) were normal in sodium-free solutions with Ca2+o calculated below 1.0 x 10(-9) mol/l. 3. When Ca2+o was subsequently increased from zero to 1.0 x 10(-3) mol/l Na+-free contractures developed slowly with unchanged RMP even at maximum contracture, at which the intracellular ultrastructure is grossly altered. 4. The contractures developed significantly faster in the presence of 3 x 10(-6) mol/l ouabain. 5. In sodium-free solutions La3+ did not influence Ca2+-dependent contractures, apart from causing an increase in time to maximum contracture. 6. It is concluded that sarcolemmal integrity is maintained in frog myocardium treated initially with Na+/Ca2+-free solutions and then with Na+-free medium containing 1 mmol/l Ca2+. 7. Our experiments indicate that sodium-free, Ca2+o-dependent contractures are mediated by the Na+/Ca2+-exchange, operation at higher rates when Na+i is increased. La3+ (1 mmol/l) probably does not compete with Ca2+ at extracellular binding sites of the exchanger. 8. The Na+/Ca2+-exchange may under certain experimental conditions be able to increase Ca2+i to cytotoxic concentrations.     

In cress roots (Lepidium sativum L.), abscisic acid prevents the development of the central cap cells into statocytes

Summary If seeds of Lepidium sativum are soaked in a 10^-4M solution of abscisic acid (ABA) for 30 min, the structural development of the central cap cells (C.C.) deviates strongly from the norm. ABA inhibits the elongation of the C.C., the sedimentation of the amyloplasts which may be caused by a higher viscosity of the cytoplasm, the formation of the stacked ER-cisternae at the distal cell pole, and the polar arrangement of the cell organelles along the gravity vector. The statistical distribution of the organelles and the arrangement of lipid droplets near the plasmalemma indicate that ABA prevents the normal development of the C.C. into statocytes.Abbreviations ABA abscisic acid - C.C. central cap cells