Mutagenesis of human adenosine deaminase to active forms that partially resist inhibition by pentostatin

Human adenosine deaminase (ADA) cDNA was randomly mutagenized in vitro and bacterial transformants were selected for resistance to the potent enzyme inhibitor, pentostatin (dCF). Cells transformed with mutant plasmids dCF-R2 and dCF-R6 were able to grow in the presence of 10(-6) M dCF, whereas 10(-11) M dCF blocked growth of cells complemented with wild-type ADA. DNA sequence analysis revealed double G/A conversions mutating Lys11 and Gln255 in dCF-R2, and Gly 31 and Glu 99 in dCF-R6, to different amino acids. Located far from the enzyme active site, these substitutions did not greatly affect the Km or Ki of the enzyme but were predicted to destabilize interactions within the enzyme structure. Mutants such as these may be useful to analysis of the stereology of inhibitor binding to ADA and toxicity of dCF.     

G-protein involvement in muscarinic receptor-stimulation of inositol phosphates in longitudinal smooth muscle from the small intestine of the guinea-pig

1. Aluminium fluoride (AlF), pertussis toxin (PTX) and cholera toxin (ChTX) have been used to examine the involvement of G-proteins during muscarinic acetylcholine receptor (AChR) stimulation of inositol phospholipid hydrolysis in fragments of longitudinal smooth muscle from the small intestine of the guinea-pig. 2. Carbachol (CCh) induced time- and concentration-dependent increases in [3H]-inositol monophosphates, [3H]-inositol (1,4) bisphosphate, [3H]-inositol (1,3,4) trisphosphate, [3H]-inositol (1,4,5) trisphosphate ([3H]-Ins (1,4,5)P3) and [3H]-inositol tetrakisphosphates measured by h.p.l.c. These increases were inhibited > 95% in the presence of the muscarinic AChR antagonist atropine (0.5 microM). 3. AlF transiently increased the basal levels of [3H]-Ins (1,4,5)P3 but increases in the levels of the other [3H]-inositol phosphates occurred more slowly. CCh-induced increases in the levels of all the [3H]-inositol phosphates were strongly inhibited in the presence of AlF. 4. PTX had no effect on basal levels of any of the [3H]-inositol phosphates but reduced the effects of CCh on these; ChTX had no effects on either basal or CCh-stimulated levels. 5. It was concluded that muscarinic AChR-stimulated increases in the levels of [3H]-inositol phosphates occur via both a PTX-sensitive G-protein and a PTX-insensitive mechanism. The actions of AlF may suggest the involvement of an inhibitory G-protein in the regulation of muscarinic AChR-stimulated inositol phospholipid turnover.     

Antioxidative activity of rosemary extract in lipid fraction of minced meat balls during storage in a freezer

The influence of ethanol rosemary extract on lipid fraction of minced meat balls during storage in the freezer was studied. The quality of stored products was evaluated sensorically by the scale method and profiling of taste and aroma. Oxidative changes were investigated on the base of the changes in malonaldehyde content. It was observed that the addition of rosemary extract delayed the oxidation of lipid fraction of products. The antioxidative effect was related to the concentration of this extract in the product. The sensory changes and their intensity in products during storage depended on the amount of the extract added and the time of storage. The addition of the extract delayed the appearance of rancid taste in products.     

Neubau der Rethebrücke,Hamburg

Mit dem Neubau der Rethebrücke, die eine Spannweite von 104,2 m aufweist, entsteht im Hamburger Hafen eine von Europas größten Doppelklappbrücken für den Straßenverkehr und die größte Doppelklappbrücke Europas für den Bahnverkehr. Getrennte Querschnitte ermöglichen eine wirtschaftliche Dimensionierung der Brücken entsprechend der unterschiedlichen Belastungen aus Bahn‐ und Straßenverkehr. Die Ausmaße der Klappen resultieren in ebenso mächtigen Klappenpfeilern, welche mit einer Tiefe im Baugrund von 21,7 m im Tidebereich der Elbe besondere Verankerungsmaßnahmen erfordern. Das Tragwerk der Brücke wird je Brückenseite aus vier sich zur Brückenmitte hin verjüngenden Fachwerkträgern gebildet. Im geschlossenen Zustand der Brücke ermöglicht eine spezielle Fingerkonstruktion in Brückenmitte, die ohne eine mechanische Verriegelung auskommt, die Übertragung positiver Momente. The new Rethebridge, Hamburg, Germany. With the erecting of the Rethebridge, which has a span of 104.2 m, the port of Hamburg gets one of Europe's largest road bridges and Europe's largest railway bridge with two movable spans (bascule bridge). The superstructure is divided in two parts, one for railway and one for road traffic, thus allowing an economic construction for the different loads. The size of the movable spans results in huge piers (21.7 m deep in ground) standing in Elbe's tidal area needing special anchorage measurements. The bridge's structure is composed of four truss girders, every bridge side, tapering to the middle of the bridge. At closed position, a special finger construction in the middle of the bridge allows the transfer of positive moments without any mechanical locking system.