Chemie: het einde

Rede uitgesproken door Prof. Dr. G.W. Canters ter gelegenheid van zijn afscheid als hoogleraar in de Biofysische Chemie aan de Universiteit Leiden op vrijdag 16 oktober 2015FWN – Publicaties zonder aanstelling Universiteit Leide

NMR study of structure and electron transfer mechanism of Pseudomonas aeruginosa azurin

Macromolecular Biochemistr

Peroxidase Activity as a Tool for Studying the Folding of c-Type Cytochromes

The peroxidase activity of c-type cytochromes increases substantially by unfolding. This phenomenon was used to study the equilibrium unfolding of ferricytochrome c. The peroxidase activity is already enhanced at low denaturant concentrations. The lowest free energy folding intermediate is easily detected by this method, while it is invisible using fluorescence or optical spectroscopy. The free energy difference between this folding intermediate and the native state depends on the strength of the sixth ligand of the heme-iron and the increase in peroxidase activity upon unfolding is shown to be a sensitive indicator of the strength of this ligand. Under fully denaturing conditions, the peroxidase activity is inhibited by protein-based ligands. It is shown that at least three different ligand groups can be responsible for this inhibition, and that at neutral or alkaline pH, the predominant ligand is not histidine. The use of peroxidase activity assays as a method to study the unfolding of cytochrome c is evaluated.Macromolecular Biochemistr

In vivo studies disprove an obligatory role of azurin in denitrification in Pseudomonas aeruginosa and show that azu expression is under control of RpoS and ANR

Microbial Biotechnolog

Effect of the protein matrix of cytochrome c in supressing the inherent peroxidase activity of its heme group

Macromolecular Biochemistr

Single-molecule fluorescence in redox chemistry

Biological and Soft Matter Physic

The peroxidase activity of cytochrome c-550 from Paracoccus versutus

Macromolecular Biochemistr

Anti-cooperativity in the two electron oxidation of the S118C disulfide dimer of azurin

Macromolecular Biochemistr

Increase of the peroxidase activity of cytochrome c-550 by the interaction with detergents

The effect was studied of detergents on the peroxidase activity of the heme-containing electron-transport protein, cytochrome c-550 from Paracoccus versutus (cytc550). Cytc550 does not interact with non-ionic or zwitterionic detergents, but its peroxidase activity is significantly enhanced in the presence of both anionic and cationic detergents. The increase in peroxidase activity is caused by (partial) unfolding of cytc550, resulting in weakening of the bond between the axial methionine ligand and the heme-iron. With sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB), the activity increases roughly 10- and 100-fold, respectively. The detergent concentration required to enhance the peroxidase activity of cytc550 consistently coincides with the critical micellisation concentration (CMC). When cytc550 carries substantial opposite charge to that of the detergent headgroup, the protein-detergent complex is formed at lower detergent concentration than the critical micellisation concentration, i.e. at acid pH for anionic detergent and at alkaline pH for cationic detergent. It is concluded that in the presence of ionic detergents, cytc550 can acquire considerable peroxidase activity. This may be exploited by applying cytc550 as an oxidative catalyst in detergent-rich environments, where regular peroxidases rapidly lose their catalytic potential. (C) 2003 Elsevier B.V. All rights reserved.Macromolecular Biochemistr