A class of mild surfactants that keep integral membrane proteins water-soluble for functional studies and crystallization
2011-04, Hovers, Jens, Odermatt, Meike, Polidori, Ange, Pucci, Bernard, Raynal, Simon, Bonneté, Francoise, Serrano-Vega, Maria J., Tate, Christopher G., Picot, Daniel, Popot, Jean-Luc, Nehmé, Rony, Bidet, Michel, Mus-Veteau, Isabelle, Bußkamp, Holger, Jung, Karl-Heinz, Marx, Andreas, Timmins, Peter A., Welte, Wolfram
Mixed protein-surfactant micelles are used for in vitro studies and 3D crystallization when solutions of pure, monodisperse integral membrane proteins are required. However, many membrane proteins undergo inactivation when transferred from the biomembrane into micelles of conventional surfactants with alkyl chains as hydrophobic moieties. Here we describe the development of surfactants with rigid, saturated or aromatic hydrocarbon groups as hydrophobic parts. Their stabilizing properties are demonstrated with three different integral membrane proteins. The temperature at which 50% of the binding sites for specific ligands are lost is used as a measure of stability and dodecyl-β-D-maltoside (‘C12-b-M’) as a reference for conventional surfactants. One surfactant increased the stability of two different G protein-coupled receptors and the human Patched protein receptor by approximately 10°C compared to C12-b-M. Another surfactant yielded the highest stabilization of the human Patched protein receptor compared to C12-b-M (13°C) but was inferior for the G protein-coupled receptors. In addition, one of the surfactants was successfully used to stabilize and crystallize the cytochrome b6 f complex from Chlamydomonas reinhardtii. The structure was solved to the same resolution as previously reported in C12-b-M.
Nucleotide analogues as probes for DNA polymerases
2005-09, Jung, Karl-Heinz, Marx, Andreas
Transmission of the genetic information from the parental DNA strand to the offspring is crucial for the survival of any living species. In nature, all DNA synthesis in DNA replication, recombination and repair is catalyzed by DNA polymerases and depends on their ability to select the canonical nucleobase pair from a pool of structurally similar building blocks. Recently, a wealth of valuable new insights into DNA polymerase mechanisms have been gained through application of carefully designed synthetic nucleotides and oligonucleotides in functional enzyme studies. The applied analogues exhibit features that differ in certain aspects from their natural counterparts and, thus, allow investigation of the involvement and efficacy of a chosen particular aspect on the entire complex enzyme mechanism. This review will focus on a depiction of the efforts that have been undertaken towards the development of nucleotide analogues with carefully altered properties. The different approaches will be discussed in the context of the motivation and the problem under investigation.
Synthesis of 4'-C-modified 2'-Deoxyribonucleoside Analogues and Oligonucleotides
2008, Marx, Andreas, Jung, Karl-Heinz
4'-C-Modified nucleotides and oligonucleotides have been explored extensively recently. The motivations for these investigations drive from the development of new drugs to investigations of complex biological processes. This review covers the common strategies for the synthesis of 4'-C-modified nucleosides that have been subsequently incorporated into oligonucleotides. After a brief depiction of two mainly followed routes for the generation of 4'-C-modified nucleosides, the synthetic efforts of the modified nucleotides are grouped into those bearing hydrophobic or polar modifications. Subsequently strategies for the incorporation of the respective nucleotides into oligonucleotides by automated DNA synthesis are discussed.