Kazimierz Strzalka, Dariusz Latowski, Susann Schaller, Malgorzata Jemioła-Rzeminska, Christian Wilhelm and Reimund Goss
Faculty of Biochemistry, Biophysics and Biotechnology, and Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa Str. 7, 30-387 Kraków, Poland
In present work we investigated influence of lipids on the activity of two de-epoxidases: violaxanthin de-epoxidase (VDE) engaged in the violaxanthin cycle and diadinoxanthin de-epoxidase (DDE) operating in the diadinoxanthin cycle. These cycles play important photoprotective role in plants and diatoms, respectively. We studied the effect of various lipids differing in their chemical character and physical properties on VDE and DDE activity. Among the parameters studied were thickness of the hydrophobic fraction of the lipid aggregates, molecular dynamics of the membrane, size of the inverted micelles and lipid solubility of violaxanthin and diadinoxanthin. We found that the main factors determining the VDE and DDE activity are the type of structure formed by lipids and solubility of xanthophylls in different lipids. The presented results indicate that VDE and DDE constitute a new family of enzymes which require presence of non-lamellar lipids for their activity.