Biomedical subjects

H Labischinski

Publications and source records attributed to H Labischinski.

58 records · Page 4Linked to original sources

PubMed1978

Shape of protein L11 from the 50S ribosomal subunit of Escherichia coli.

Protein L11 from the 50S ribosomal subunit of Escherichia coli A19 was purified by a method using nondenaturing conditions. Its shape in solution was studied by hydrodynamic and low-angle x-ray scattering experiments. The results from both methods are in good agreement. In buffers similar to the ribosomal reconstitution buffer, the protein is monomeric at concentrations up to 3 mg/mL and has a molecular weight of 16 000-17 000. The protein molecule resembles a prolate ellipsoid with an axial ratio of 5-6:1 a radius of gyration of 34 A, and a maximal length of 150 A. From the low-angle x-ray diffraction data, a more refined model of the protein molecule has been constructed consisting of two ellipsoids joined by their long axes.

Escherichia coli↗

PubMedDate not supplied

Conformational and topological aspects of the three-dimensional architecture of bacterial peptidoglycan.

An atomic model of the conformation of peptidoglycan was taken as the basis for an analysis of packing patterns of the peptidoglycan strands in two- and three-dimensional arrangements. For the sake of clarity, glycan strands were approximated by cylindrical rods around which a continuous helix of possible peptide cross-linkage sites was arranged. Using the packing patterns obtained, several important properties of the murein network could be explained. These include variations in the degree of cross-linking in Gram-negative and Gram-positive bacteria and an estimation of the number of peptide monomers, di/trimers and oligomers present. Furthermore, our model is compatible with the well known flexibility of the murein fabric and the distinct elastic properties of the cell wall in gram-positive cocci and rod-shaped bacteria.

Bacteria↗

PubMedDate not supplied

On the relationships between molecular conformation, affinity towards penicillin-binding proteins, and biological activity of penicillin G-sulfoxide.

The binding capacity of penicillin G-sulfoxide towards the penicillin-binding proteins (PBP) of Staphylococcus aureus H was studied. The sulfoxide and its parent compound, penicillin G, differ only in two aspects, the sulfur-bound oxygen and an altered conformation of the five-membered thiazolidine-ring system. These minor alterations of the penicillin structure resulted in a drastical decrease of binding activity (about two orders of magnitude) of the sulfoxide derivative towards its target enzymes. Furthermore, the sulfoxide did not exhibit the selectivity of subinhibitory doses for PBP 3, as could be observed for penicillin G. The biological consequences of this behaviour were monitored via growth curves, uptake of cell wall label, and analysis of the cell wall. Binding studies revealed that comparable growth inhibition and impairment of cell wall label uptake were achieved by at least a 100-fold higher penicillin G-sulfoxide concentration, compared to its parent compound. In cell wall analysis, the application of high doses of the antibiotics, i.e. nearly saturated PBP, verified the above mentioned observation. Surprisingly, small but significant differences in cell wall composition occurred using subinhibitory doses, probably due to the altered affinity towards PBP 3, supporting the hypothesis of an important role of this PBP in peptidoglycan transpeptidation.

Bacterial Proteins↗

PubMedDate not supplied

Coprinol, a new antibiotic cuparane from a Coprinus species.

Coprinol, a new antibacterial cuparane, was isolated from fermentations of a Coprinus sp. Its biological activities were investigated and its structure was elucidated by spectroscopic methods. The new antibiotic exhibited activitiy against multidrug-resistant Gram-positive bacteria in vitro. Two derivatives were synthesized and their activities compared to the parent compound.

Adenocarcinoma↗