title: Computer simulation of native epidermal enzyme structures in the presence and absence of hydrogen peroxide (H2O2): potential and pitfalls.
abstract: The human epidermis is especially vulnerable to oxidative stress, which in turn leads to oxidation of important antioxidant enzymes, other proteins, and peptides. Molecular dynamic computer modelling is a new powerful tool to predict or confirm oxidative stress-mediated structural changes consequently altering the function of enzymes/proteins/peptides. Here we used examples of important epidermal antioxidant enzymes before and after hydrogen peroxide (H(2)O(2))-mediated oxidation of susceptible amino-acid residues (i.e. tryptophan, methionine, cysteine, and selenocysteine), which can affect enzyme active sites, cofactor binding, or dimerization/tetramerization domains. Computer modelling predicts that enzyme active sites are altered by H(2)O(2)-mediated oxidation in thioredoxin reductase (TR) and acetylcholinesterase (AchE), whereas cofactor nicotinamide adenine dinucleotide phosphate (reduced form) binding is affected in both catalase and TR but not in glutathione peroxidase. Dimerization is prevented in catalase. These structural changes lead to impaired functionality. Fourier transform-Raman- and Fluorescence spectroscopy together with enzyme kinetics support the results. There are limitations of modelling as demonstrated on the AchE substrate-binding domain, where the computer predicted deactivation, which could not be confirmed by enzyme kinetics. Computer modelling coupled with classical biochemical techniques offers a new powerful tool in cutaneous biology to explore oxidative stress-mediated metabolic changes in the skin.
authors.affiliation: Clinical and Experimental Dermatology, Department of Biomedical Sciences, University of Bradford, Bradford, UK.
authors.forename: Nicholas C J
authors.initials: NC
authors.lastname: Gibbons
authors.forename: John M
authors.initials: JM
authors.lastname: Wood
authors.forename: Hartmut
authors.initials: H
authors.lastname: Rokos
authors.forename: Karin U
authors.initials: KU
authors.lastname: Schallreuter
mesh_terms: D003198:Computer Simulation; D004798:Enzymes / Q000737:chemistry; D004817:Epidermis / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008954:Models, Biological; D015394:Molecular Structure; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004798:Enzymes; D006861:Hydrogen Peroxide; D010088:Oxidoreductases