Our Research Interests: Biophysics and biochemistry of membrane proteins: membrane bound enzymes, transporters, receptors; solid-state NMR

Recent Research Highlights

Time resolved solid-state NMR allows to follow enzyme kinetics of the transmembrane lipid regulator diacyclglycerolkinase from E.coli

Ullrich, Hellmich, Ullrich & Glaubitz (2011) Nature Chem. Biol. Epub ahead of print.  

The integral membrane protein diacylglycerol kinase from E.coli transfers the gamma-phosphate from ATP to diacylglcerol to yield phosphatidic acid. It couples two reactions in two phases at the membrane interface: ATP hydrolysis in the aqueous phase and lipid phosphorylation in the lipid phase. We have used real-time 31P-MAS NMR to follow both reactions simultaneously. Kinetic analysis, substrate titration and the use of ATP and phosphate analogs did allow to obtain novel insight into the functional mechanism of DGK and allows to draw conclusions about the phosphoryl transfer mechanism catalyzed by DGK. This work also highlights the potential of solid-state NMR for the investigation of reactions at the lipid bilayer interface.

His-Asp Cluster revealed in Proteorhodopsin

Hempelmann, Hölper, Verhoefen, Wörner, Köhler, Fiedler, Pfleger, Wachtveitl & Glaubitz (2011) J. Am. Chem. Soc. Epub ahead of print. 

Solid-state NMR, optical spectroscopy and BLM has been used to identify the role of the His75-Asp97 cluster found within the PR family. His75 was identified as the main source of stabilizing the high pKa of Asp97 through a pH dependent H-bond. On the other hand, His75 was found to slow down the photocycle of PR which indicates that evolution has not optimized PR for fast proton transfer which raises questions about the true function of PR in vivo ().  

Dynamics of Proteorhodopsin in Lipid Bilayers

Yang, Aslimovska & Glaubitz (2011) J. Am. Chem. Soc. Epub ahead of print. 

A dynamic profile of 7TM membrane protein proteorhodopsin within lipid bilayers was obtained by using J-coupling and dipolar based MAS-NMR experiments. The effect of alterations in lipid bilayer elasticity as well as the influence of hydration onto flexible loops, structured loops and transmembrane domains has been investigated. Our data allow to identify regions which undergo enhanced thermal fluctuations which might have functional importance for structural changes during the photocycle.