Search PubMed⌕ Search

Biomedical subjects

Karl-Erich Jaeger

Publications and source records attributed to Karl-Erich Jaeger.

23 records · Page 2Linked to original sources
PubMed2003

Extracellular lipases from Bacillus subtilis: regulation of gene expression and enzyme activity by amino acid supply and external pH.

Bacillus subtilis secretes two lipases LipA and LipB into the culture medium. Both enzyme genes were differentially expressed depending on the growth conditions as determined by activity assays and Western blotting in B. subtilis mutant strains lipA, lipB, and the corresponding lipA/lipB double mutant. In minimal medium, LipA was produced at wild-type level in a lipB mutant, however, no LipB protein was detected in a lipA mutant. Interestingly, LipA was produced and secreted at wild-type level in rich medium, but the enzyme remained enzymatically inactive, presumably being caused by a shift of the growth medium to acid pH. Furthermore, expression of the lipase genes was studied using transcriptional fusions with the lacZ reporter gene. The expression of lipA was repressed by high amino acid concentrations, whereas the lipB gene expression remained unaffected.

Amino Acids↗
PubMed2003

Structural basis of carbohydrate recognition by the lectin LecB from Pseudomonas aeruginosa.

The crystal structure of Pseudomonas aeruginosa fucose-specific lectin LecB was determined in its metal-bound and metal-free state as well as in complex with fucose, mannose and fructopyranose. All three monosaccharides bind isosterically via direct interactions with two calcium ions as well as direct hydrogen bonds with several side-chains. The higher affinity for fucose is explained by the details of the binding site around C6 and O1 of fucose. In the mannose and fructose complexes, a carboxylate oxygen atom and one or two hydroxyl groups are partly shielded from solvent upon sugar binding, preventing them from completely fulfilling their hydrogen bonding potential. In the fucose complex, no such defects are observed. Instead, C6 makes favourable interactions with a small hydrophobic patch. Upon demetallization, the C terminus as well as the otherwise rigid metal-binding loop become more mobile and adopt multiple conformations.

Binding Sites↗
PubMed2002

Lipases for biotechnology.

Lipases constitute the most important group of biocatalysts for biotechnological applications. The high-level production of microbial lipases requires not only the efficient overexpression of the corresponding genes but also a detailed understanding of the molecular mechanisms governing their folding and secretion. The optimisation of industrially relevant lipase properties can be achieved by directed evolution. Furthermore, novel biotechnological applications have been successfully established using lipases for the synthesis of biopolymers and biodiesel, the production of enantiopure pharmaceuticals, agrochemicals, and flavour compounds.

Agrochemicals↗
PubMedDate not supplied

Novel biocatalysts for white biotechnology.

White Biotechnology uses microorganisms and enzymes to manufacture a large variety of chemical products. Therefore, the demand for new and useful biocatalysts is steadily and rapidly increasing. We have developed methods for the isolation of new enzyme genes, constructed novel expression systems, and optimized existing enzymes for biotechnological applications by methods of directed evolution. Furthermore, we have isolated and characterized biocatalysts relevant for the preparation of enantiopure compounds.

Biotechnology↗