Yearbook 2009

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Eggs attract sperm by the release of chemical factors (chemoattractants). Sperm navigate in the chemoattractant gradient surrounding the egg, a process called chemotaxis. Sperm of the sea urchin Arbacia punctulata display an extreme sensitivity for their chemoattractant. The sperm can respond to stimulation by a single attractant molecule. An atypical cyclic nucleotide-gated ion channel (CNGK) in the sperm flagellum is key for the single-molecule sensitivity. The chemoattractant triggers the synthesis of the intracellular messenger cGMP. The structurally unique CNGK-channel is activated by small changes in intracellular cGMP concentration and initiates the chemotactic signaling cascade. more
Biomolecular motors are mechano-enzymes capable of converting chemical energy into directed motion. Recent advances in the biophysical understanding of these motors have raised the possibility that they might find applications as nanomachines in synthetic environments. For example, they could be used as molecule-sized robots that build up and manipulate nanostructures, detect chemicals or sort molecular reagents. more
Novel NMR spectroscopic parameters allowed to determine not only the average structure of the protein ubiquitin but in addition the description of a faithful ensemble of the protein in solution. The ensemble reflected especially the previously inaccessible time window between 5 ns and 50 µs. The ensemble revealed the mechanism of protein protein recognition for this protein. If this was general new strategies for modulation of protein protein recognition would open up that could be used for more efficient drug development. more
Unpaired electrons possess a magnetic moment, which is about three orders of magnitude larger than the one of a proton. This moment can be employed as a highly sensitive probe in EPR spectroscopic investigations to gain structural information at the atomic up to the nanometer scale. The experiments provide insights into structural changes of biomolecules during their functional states. We have developed and implemented multi-frequency EPR methodologies to investigate enzymatic reactions in proteins and oligonucleotides. more
An increasing number of people are living in the growing cities of this world. This results in a rapid growth of the fraction of anthropogenic emissions of pollutants from such megacities. For a detailed investigation of the particulate and gaseous substances in the atmosphere in such a city and in its vicinity, extensive measurements were performed in the metropolitan area of Paris. The study of the transformation and aging processes of such species was done using modern instrumentation in a ground measurement station, on a research aircraft, and on a mobile laboratory for aerosol research. more

The air above the green lung rainforest

Max Planck Institute for Chemistry Andreae, Meinrat O.; Trebs, Ivonne; Meixner, Franz X.; Kesselmeier, Jürgen; Pöschl, Ulrich
The exchange of reactive trace gases and aerosol particles between biosphere and atmosphere contributes substantially to chemical and physical processes in the atmosphere. Recent investigations provide insight into the interplay of reactive nitrogen compounds, volatile organics and aerosol formation. The results underline the major importance of the Amazonian rainforest for the global climate and the Earth system. more
Nerve fibers of vertebrates are enveloped by a lamellar membrane sheath referred to as myelin. Myelin acts as an electrical insulator and is of fundamental importance for the nerve conduction. By use of relaxographic magnetic resonance imaging, it is feasible to obtain spatial information about the myelin sheath through the observation of intercalated water molecules. This leads to a novel modality for microstructural investigations of the living brain. more
How should modern society fight the evasion of taxes and fees? The economic model suggests that we should set proper incentives by threatening with (and implementing) fines and legal sanctions. But does this approach work? Could we design alternative and probably more successful policies that rely on moral appeals and social norms? A natural field experiment of the Max Planck Institute for Research on Collective Goods in the domain of TV license fee evasion tries to answer these questions. more
Magnetic nanoparticles are key components in many novel bio- and nanotechnological applications. These applications require highly uniform particle dimensions. The available chemical processes are unable to produce such crystals. Magnetotactic bacteria have resolved the complicated equation of forming such perfect particles under physiological conditions. This performance is analyzed by determining the role that key biological determinants play in the control of the properties of the biological magnets. The Mms6 protein was shown to specifically control magnetite size in vitro . more

Automated chemical synthesis of carbohydrates

Max Planck Institute of Colloids and Interfaces Seeberger, Peter H.; Kamena, Faustin; Lepenies, Bernd; Hartmann, Laura
Carbohydrates are complex molecules that are extremely difficult to synthesize by both chemical and enzymatic means. This is one of the main reasons why the entire field of glycomics is less prominent than genomics and proteomics. In the following report we discuss the introduction of the automatic chemical synthesis of carbohydrates and its impact on glycoscience. more
Modern medical diagnostics and brain research would be unthinkable without magnetic resonance imaging (MRI). In addition to traditional imaging, which reveals anatomical structures, functional MRI (fMRI) has become a valuable tool. It comes close to allowing us to watch the brain at work and has contributed considerably to the advances in human cognitive neuroscience. However, fMRI is an indirect method, as it measures a surrogate signal, based on hemodynamics. Smart contrast agents (SCAs) shall overcome this limitation and allow a direct access to neuronal activity. more
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