Max Planck Institute for Chemistry
Max Planck Institute for Chemistry
The Max Planck Institute for Chemistry is a scientific research institute under the Max-Planck-Gesellschaft.Basic research in chemistry and related subjects is carried out at the four departments of the institute. The departments are independently led by their Directors. Wikipedia.
Jahns P.,Heinrich Heine University Düsseldorf |
Holzwarth A.R.,Max Planck Institute for Chemistry
Biochimica et Biophysica Acta - Bioenergetics | Year: 2012
Photoprotection of photosystem II (PSII) is essential to avoid the light-induced damage of the photosynthetic apparatus due to the formation of reactive oxygen species (= photo-oxidative stress) under excess light. Carotenoids are known to play a crucial role in these processes based on their property to deactivate triplet chlorophyll ( 3Chl *) and singlet oxygen ( 1O 2 *). Xanthophylls are further assumed to be involved either directly or indirectly in the non-photochemical quenching (NPQ) of excess light energy in the antenna of PSII. This review gives an overview on recent progress in the understanding of the photoprotective role of the xanthophylls zeaxanthin (which is formed in the light in the so-called xanthophyll cycle) and lutein with emphasis on the NPQ processes associated with PSII of higher plants. The current knowledge supports the view that the photoprotective role of Lut is predominantly restricted to its function in the deactivation of 3Chl *, while zeaxanthin is the major player in the deactivation of excited singlet Chl ( 1Chl *) and thus in NPQ (non-photochemical quenching). Additionally, zeaxanthin serves important functions as an antioxidant in the lipid phase of the membrane and is likely to act as a key component in the memory of the chloroplast with respect to preceding photo-oxidative stress. This article is part of a Special Issue entitled: Photosystem II. © 2011 Elsevier B.V. All rights reserved.
Marsh D.,Max Planck Institute for Chemistry
Biophysical Journal | Year: 2012
Negatively charged phospholipids are an important component of biological membranes. The thermodynamic parameters governing self-assembly of anionic phospholipids are deduced here from isothermal titration calorimetry. Heats of demicellization were determined for dioctanoyl phosphatidylglycerol (PG) and phosphatidylserine (PS) at different ionic strengths, and for dioctanoyl phosphatidic acid at different pH values. The large heat capacity (ΔC o P ∼ -400 J.mol -1 K -1 for PG and PS), and zero enthalpy at a characteristic temperature near the physiological range (T ∼ 300 K for PG and PS), demonstrate that the driving force for self-assembly is the hydrophobic effect. The pH and ionic-strength dependences indicate that the principal electrostatic contribution to self-assembly comes from the entropy associated with the electrostatic double layer, in agreement with theoretical predictions. These measurements help define the thermodynamic effects of anionic lipids on biomembrane stability. © 2012 Biophysical Society.
Eremets M.I.,Max Planck Institute for Chemistry |
Troyan I.A.,Max Planck Institute for Chemistry
Nature Materials | Year: 2011
Molecular hydrogen is expected to exhibit metallic properties under megabar pressures. This metal is predicted to be superconducting with a very high critical temperature, Tc, of 200-400K (ref.), and it may acquire a new quantum state as a metallic superfluid and a superconducting superfluid. It may potentially be recovered metastably at ambient pressures. However, experiments carried out at low temperatures, T<100K (refs,), showed that at record pressures of 300GPa, hydrogen remains in the molecular insulating state. Here we report on the transformation of normal molecular hydrogen at room temperature (295K) to a conductive and metallic state. At 200GPa the Raman frequency of the molecular vibron strongly decreased and the spectral width increased, evidencing a strong interaction between molecules. Deuterium behaved similarly. Above 220GPa, hydrogen became opaque and electrically conductive. At 260-270GPa, hydrogen transformed into a metal as the conductance of hydrogen sharply increased and changed little on further pressurizing up to 300GPa or cooling to at least 30K; and the sample reflected light well. The metallic phase transformed back at 295K into molecular hydrogen at 200GPa. This significant hysteresis indicates that the transformation of molecular hydrogen into a metal is accompanied by a first-order structural transition presumably into a monatomic liquid state. Our findings open an avenue for detailed and comprehensive studies of metallic hydrogen. © 2011 Macmillan Publishers Limited. All rights reserved.
Hulsmann B.B.,Max Planck Institute for Chemistry |
Labokha A.A.,Max Planck Institute for Chemistry |
Gorlich D.,Max Planck Institute for Chemistry
Cell | Year: 2012
Nuclear pore complexes (NPCs) maintain a permeability barrier between the nucleus and the cytoplasm through FG-repeat-containing nucleoporins (Nups). We previously proposed a "selective phase model" in which the FG repeats interact with one another to form a sieve-like barrier that can be locally disrupted by the binding of nuclear transport receptors (NTRs), but not by inert macromolecules, allowing selective passage of NTRs and associated cargo. Here, we provide direct evidence for this model in a physiological context. By using NPCs reconstituted from Xenopus laevis egg extracts, we show that Nup98 is essential for maintaining the permeability barrier. Specifically, the multivalent cohesion between FG repeats is required, including cohesive FG repeats close to the anchorage point to the NPC scaffold. Our data exclude alternative models that are based solely on an interaction between the FG repeats and NTRs and indicate that the barrier is formed by a sieve-like FG hydrogel. © 2012 Elsevier Inc.
Sander R.,Max Planck Institute for Chemistry
Atmospheric Chemistry and Physics | Year: 2015
Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles. Therefore, it is necessary to understand the distribution between the phases. According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution. Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format. The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references. It is also available at http://www.henrys-law.org. © Author(s) 2015.
Losi A.,University of Parma |
Gartner W.,Max Planck Institute for Chemistry
Annual Review of Plant Biology | Year: 2012
Photoreceptor flavoproteins of the LOV, BLUF, and cryptochrome families are ubiquitous among the three domains of life and are configured as UVA/blue-light systems not only in plantsmdashtheir original arenamdashbut also in prokaryotes and microscopic algae. Here, we review these proteins' structure and function, their biological roles, and their evolution and impact in the living world, and underline their growing application in biotechnologies. We present novel developments such as the interplay of light and redox stimuli, emerging enzymatic and biological functions, lessons on evolution from picoalgae, metagenomics analysis, and optogenetics applications. © 2012 by Annual Reviews. All rights reserved.
Poschl U.,Max Planck Institute for Chemistry |
Shiraiwa M.,Max Planck Institute for Chemistry
Chemical Reviews | Year: 2015
Multiphase chemistry deals with chemical reactions, transport processes, and transformations between gaseous, liquid, and solid matter. After deposition, viable bioparticles can trigger and other particles can interfere with metabolic activity and biological reproduction or disease. These effects may stimulate or suppress further emissions, thus closing a biogeochemical cycle and related feedback loops in the Earth system. The multiphase processes involved in the cycling of gases, aerosols, clouds, and precipitation are important for the evolution, current state, and future development of the atmosphere and climate as well as the biosphere and public health. Aerosol particles are ubiquitous in the atmosphere and affect climate by scattering or absorption of light and serving as nuclei for cloud droplets, ice crystals, and precipitation.
Marsh D.,Max Planck Institute for Chemistry
Biochimica et Biophysica Acta - Biomembranes | Year: 2010
Mixtures of phospholipids with cholesterol are able to form liquid-ordered phases that are characterised by short-range orientational order and long-range translational disorder. These Lo-phases are distinct from the liquid-disordered, fluid Lα-phases and the solid-ordered, gel Lβ-phases that are assumed by the phospholipids alone. The liquid-ordered phase can produce spatially separated in-plane fluid domains, which, in the form of lipid rafts, are thought to act as platforms for signalling and membrane sorting in cells. The areas of domain formation are defined by the regions of phase coexistence in the phase diagrams for the binary mixtures of lipid with cholesterol. In this paper, the available binary phase diagrams of lipid-cholesterol mixtures are all collected together. It is found that there is not complete agreement between different determinations of the phase diagrams for the same binary mixture. This can be attributed to the indirect methods largely used to establish the phase boundaries. Intercomparison of the various data sets allows critical assessment of which phase boundaries are rigorously established from direct evidence for phase coexistence. © 2010 Elsevier B.V. All rights reserved.
Vereecken L.,Max Planck Institute for Chemistry |
Francisco J.S.,Purdue University
Chemical Society Reviews | Year: 2012
The chemistry of the atmosphere encompasses a vast number of reactions acting on a plethora of intermediates. These reactions, occurring sequentially and in parallel, give rise to intertwined and irreducible mechanisms describing the complex chemical transformations of organic and inorganic compounds in the atmosphere. The complexity of this system is that it requires combined experimental, theoretical, and modeling approaches to elucidate the characteristics of the individual reactions, and their mutual interaction. In this review, we describe recent results from quantum chemical and theoretical kinetic studies of relevance to atmospheric chemistry. The review first summarizes the most commonly used theoretical methodologies. It then examines the VOC oxidation initiation channels by OH, O3, NO3 and Cl, followed by the reactions of the alkyl, alkoxy, alkylperoxy and Criegee intermediates active in the subsequent oxidation steps. Specific systems such as the oxidation of aromatics and the current state of knowledge on OH-regeneration in VOC oxidation are also discussed, as well as some inorganic reactions. © The Royal Society of Chemistry 2012.
Drew S.C.,Max Planck Institute for Chemistry |
Barnham K.J.,University of Melbourne
Accounts of Chemical Research | Year: 2011
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. Within the brain, senile plaques, which comprise extracellular deposits of the amyloid-β peptide (Aβ), are the most common pathological feature of AD. A high concentration of Cu 2+ is found within these plaques, which are also areas under oxidative stress. Laboratory work has shown that in vitro Aβ will react with Cu2+ to induce peptide aggregation and the production of reactive oxygen species. As such, this interaction offers a possible explanation for two of the defining pathological features observed in the AD brain: the presence of amyloid plaques, which consist largely of insoluble Aβ aggregates, and the abundant oxidative stress therein. Researchers have accordingly put forth the "metals hypothesis" of AD, which postulates that compounds designed to inhibit Cu2+/Aβ interactions and redistribute Cu2+ may offer therapeutic potential for treating AD.Characterization of the pH-dependent Cu2+ coordination of Aβ is fundamental to understanding the neurological relevance of Cu 2+/Aβ interactions and aiding the design of new therapeutic agents. In an effort to shed light on the problem, many experimental and theoretical techniques, using a variety of model systems, have been undertaken. The preceding decade has seen numerous conflicting spectroscopic reports concerning the nature of the Cu2+/Aβ coordination. As the number of studies has grown, the nature of the pH-dependent ligand environment surrounding the Cu2+ cation has remained a point of contention. In large part, the difficulties can be attributed to inappropriate choices of the model system or to methods that are incapable of quantitatively delineating the presence and identity of multiple Cu2+ coordination modes.Electron paramagnetic resonance (EPR) is the method of choice for studying paramagnetic metal-protein interactions. With the introduction of site-specific 15N, 17O, and 13C isotopic labels and the application of advanced techniques, EPR is capable of eliminating much of the ambiguity. Recent EPR studies have produced the most definitive picture of the pH-dependent Cu2+ coordination modes of Aβ and enabled researchers to address the inconsistencies present in the literature.In this Account, we begin by briefly introducing the evidence for a role of Cu 2+ in AD as well as the potential physiological and therapeutic implications of that role. We then outline the EPR methodology used to resolve the molecular details of the Cu2+/Aβ interactions. No drugs are currently available for altering the course of AD, and existing therapies only offer short-term symptomatic relief. This focused picture of the role of Cu 2+ in AD-related plaques offers welcome potential for the development of new methods to combat this devastating disease. © 2011 American Chemical Society.