PubMed Health⌕ Search

Biomedical subjects

Bernd Simon

Publications and source records attributed to Bernd Simon.

23 records · Page 2Linked to original sources
PubMed2003

Establishing the yeast Saccharomyces cerevisiae as a system for expression of human proteins on a proteome-scale.

Structural genomics requires the application of a standardised process for overexpression of soluble proteins that allows high-throughput purification and analysis of protein products. We have developed a highly parallel approach to protein expression, including the simultaneous expression screening of a large number of cDNA clones in an appropriate vector system and the use of a protease-deficient host strain. A set of 221 human genes coding for proteins of various sizes with unknown structures was selected to evaluate the system. We transferred the cDNAs from an E. coli vector to the yeast expression vector by recombinational cloning, avoiding time-consuming recloning steps and the use of restriction enzymes in the cloning process. The subcloning yield was 95%, provided that a PCR fragment of the correct size could be obtained. Sixty percent of these proteins were expressed as soluble products at detectable levels and 48% were successfully purified under native conditions using the His6 tag fusion. The advantages of the developed yeast-based expression system are the ease of manipulation and cultivation of S. cerevisiae in the same way as with prokaryotic hosts and the ability to introduce post-translational modifications of proteins if required, thus being an attractive system for heterologous expression of mammalian proteins. The expression clones selected in this screening process are passed on to the fermentation process in order to provide milligram amounts of proteins for structure analysis within the 'Berlin Protein Structure Factory'. All data generated is stored in a relational database and is available on our website (http://www.proteinstrukturfabrik.de).

Aspartic Acid Endopeptidases↗
PubMed2003

Intra-oesophageal pH profiles and pharmacokinetics of pantoprazole and esomeprazole: a crossover study in patients with gastro-oesophageal reflux disease.

AIM: To compare the effect of pantoprazole and esomeprazole on intra-oesophageal pH and investigate their pharmacokinetics in patients with symptomatic gastro-oesophageal reflux disease (GORD). METHODS: Double-blind, randomized, two-period crossover study. Caucasian men with symptomatic GORD (n=48) were selected on the basis of clinical records of typical GORD symptoms, confirmed by a pathological reflux time (oesophageal pH<4 for > or =6% of the time). They received oral pantoprazole 40 mg once daily (od) or esomeprazole 40 mg od for seven days. Continuous 24 h oesophageal pH-metry was performed at baseline and day 7. Evaluations included: pre- and post-treatment differences in the percentage of time with pH<4.0 and <3.0 between baseline and day 7; area under the curve (AUC), Cmax, and T(1/2); point estimates and 90% confidence intervals (CI) on days 1 and 7, calculated for ratios of the AUC and Cmax. RESULTS: Both drugs decreased the mean total number of reflux episodes and reduced the percentage of reflux time within 24 h to <3%. No pathological reflux was detectable after repeated administration of either drug. The 90% CI were within the predefined range at all time points; thus, equivalence of pantoprazole and esomeprazole was concluded. For pantoprazole, Cmax and AUC were unchanged on day 7 vs day 1, confirming its high and constant bioavailability. For esomeprazole, Cmax and AUC were increased on day 7 vs day 1 by 80% and 50%, respectively, indicating low initial bioavailability. No clinically relevant side effects were seen for either drug. CONCLUSION: Pantoprazole and esomeprazole have equivalent effect on oesophageal pH, since no pathological reflux was detected after treatment with either drug. For esomeprazole, the Cmax and AUC increased after multiple dosing; for pantoprazole the pharmacokinetics were predictable and independent of the number of administered doses.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2003

Respect for group members: intragroup determinants of collective identification and group-serving behavior.

This experiment examined how (disrespectful vs. respectful) treatment and (negative vs. positive) performance evaluation, both received from the same fellow group members, affects collective identification and willingness to engage in group-serving behavior. It was predicted and found that respectful as opposed to disrespectful intragroup treatment increased collective identification and willingness to engage in group-serving behavior in the immediate group situation, irrespective of whether intragroup evaluation was positive or negative. There was also evidence of a mediating role of collective identification. Regression analyses based on the measurement of perceived intragroup treatment and perceived intragroup evaluation as continuous variables corroborated these findings but also pointed to limits of the positive effects of respectful intragroup treatment. Finally, the interrelation of treatment and evaluation by fellow group members as two possible components of intragroup respect are discussed as well as the political dimension of research on intragroup respect.

Adult↗
PubMed2002

The structures of the active center in dark-adapted bacteriorhodopsin by solution-state NMR spectroscopy.

The two forms of bacteriorhodopsin present in the dark-adapted state, containing either all-trans or 13-cis,15-syn retinal, were examined by using solution state NMR, and their structures were determined. Comparison of the all-trans and the 13-cis,15-syn forms shows a shift in position of about 0.25 A within the pocket of the protein. Comparing this to the 13-cis,15-anti chromophore of the catalytic cycle M-intermediate structure, the 13-cis,15-syn form demonstrates a less pronounced up-tilt of the retinal C12[bond]C14 region, while leaving W182 and T178 essentially unchanged. The N[bond]H dipole of the Schiff base orients toward the extracellular side in both forms, however, it reorients toward the intracellular side in the 13-cis,15-anti configuration to form the catalytic M-intermediate. Thus, the change of the N[bond]H dipole is considered primarily responsible for energy storage, conformation changes of the protein, and the deprotonation of the Schiff base. The structural similarity of the all-trans and 13-cis,15-syn forms is taken as strong evidence for the ion dipole dragging model by which proton (hydroxide ion) translocation follows the change of the dipole.

Amino Acid Sequence↗