Status report of the new carbonate clumped laboratory of Isotope Climatology and Environmental Research Center (ICER), Debrecen, Hungary

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A potential groundwater aquifer for palaeoclimate reconstruction: Turonian aquifer, Tadla basin, Morocco

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Protontranszfer fehérjében. = Protein controlled proton transfer.

A protonok vezetése kulcsfontosságú számos membrán-csatorna és energiaátalakító fehérje működésében. A fotoszintetizáló baktériumok reakciócentrumával elvégzett vizsgálatainkból kiindulva próbáltuk megérteni azokat az alapelveket, amelyeket a Természet alkotott, és használ a nagy hatótávolságú protontranszfer során. Megértettük, hogy a protonokat a hidrogen-hídakkal hálózatba szerveződött aminosavak és protonált vízmolekulák (Eigen- és Zünder-ionok) veszik fel, vezetik és adják le a fehérje jól meghatározott részein. Az ilyen hálózatok képesek a protonokat időlegesen tárolni is, és szükség esetén innen felhasználni ("proton-szivacs" koncepció). A proton-klaszter elemei között nagy (60 meV) a kölcsönhatási energia , és ezek együttesen, nem-kooperatív módon veszik fel (adják le) a protonokat. Kimutattuk, hogy ez a proton-hálózat az egész citoplazmikus térrészre kiterjed. Ez a szerveződés és működési elv általános lehet az élőlényekben, mert hasonló protonvezetés figyelhető meg más energia-átalakító fehérjében is (bakteriorodopszin, citokróm c oxidáz, emberi szén anhidráz stb.). A protonok a fehérje jól meghatározott proton-kapuin keresztül vétetnek fel, ill. adódnak le, amely kapukat és protonvezetési utakat a fehérje elektrosztatikája és mozgása (dinamikája) irányítja. A munkánk eredményeivel közelebb jutottunk annak megértéséhez, milyen elvek alapján működik élő rendszerben a protonvezetés, és esélyt látunk arra, hogy ennek felhasználásával mesterségesen protonvezetési molekuláris rendszereket tervezzünk. | Transfer and transport of protons are key processes in several membrane channels and bioenergetic proteins. Based on studies of light-induced proton uptake and release in reaction center (RC) protein of photosynthetic bacteria, an attempt is made to draw some conclusions about how Nature designs long distance, proton transport functionality. The proton is conducted through hydrogen bonded chains of amino acids and protonated water (Zündel and Eigen ions) and can be even stored in this network (?proton sponge?) for later use. The interaction energy among the constituents of the cluster is larger (in the range of 60 meV) than supposed earlier by electrostatic calculations and FTIR measurements. The uptake and conduction of protons in the cluster are collective and non-cooperative process. The network extends through the whole cytoplasmic side of the RC protein. We prefer the prevalence of protonated water rather than amino acid hydrogen bonded chains in the proton conduction as revealed by investigations of numerous site directed mutants of the RC and other proton (water) translocating biomolecules like (aquaporin), bacteriorhopsin, cytochrome c oxidase and human carbonic anhydrase. We could demonstrate that the uptake and release of protons occurred through well defined gates and could be controlled (facilitated or blocked) by electrostatics and dynamics of the protein. We came closer to understand the design of the natural system and got the chance to start to construct artificial proton translocating molecular systems

Functional Nanohybrid Materials from Photosynthetic Reaction Center Proteins

Application of technical developments in biology and vice versa or biological samples in technology led to the development of new types of functional, so-called “biohybrid” materials. These types of materials can be created at any level of the biological organization from molecules through tissues and organs to the individuals. Macromolecules and/or molecular complexes, membranes in biology, are inherently good representatives of nanosystems since they fall in the range usually called “nano.” Nanohybrid materials provide the possibility to create functional bionanohybrid complexes which also led to new discipline called “nanobionics” in the literature and are considered as materials for the future. In this publication, the special characteristics of photosynthetic reaction center proteins, which are “nature’s solar batteries,” will be discussed in terms of their possible applications for creating functional molecular biohybrid materials

Combined use of conventional and clumped carbonate stable isotopes to identify hydrothermal isotopic alteration in cave walls

Alteration of conventional carbonate stable isotopes (δ 18 O, δ13 C) in cave walls has been shown to be a useful tool to identify cave formation driven by deep-seated processes, i.e., hypogene karstification. If combined with a prior information on the paleowater stable isotope composition, further insights can be obtained on the temperature and the source of the paleowater. Clumped isotope composition (Δ 47 ) of carbonates is an independent measurement of temperature, and if combined with the conventional stable isotopes, can provide information on the paleowater stable isotope composition. On the example of Provalata Cave (N. Macedonia), we apply for the first time, both conventional and clumped stable isotope analysis, and identify two different isotope alteration trends, reflecting two distinct hydrothermal events: an older, hotter one, where isotope alteration was likely related to isotope diffusion, lowering the δ 18 O values of the carbonate; and a younger one, related to the cave formation by low-temperature CO 2 -rich thermal waters, with dissolution-reprecipitation as the alteration mechanism, causing decrease in δ 18 O values, and unexpected increase in δ 13 C values. The findings are further corroborated by additional insight from optical petrography and cathodoluminescence microscopy, as well as fluid inclusion analysis of secondary calcite crystals related to the cave forming phase

Real-Time Sensing of Hydrogen Peroxide by ITO/MWCNT/Horseradish Peroxidase Enzyme Electrode

The accurate and sensitive determination of H2O2 is very important in many cases because it is a product of reactions catalysed by several oxidase enzymes in living cells and it is essential in environmental and pharmaceutical analyses. The fabrication of enzyme protein activity based biosensors is a very promising way for this purpose because the function of biological molecules is very specific, sensitive, and selective. Horseradish peroxidase (HRP) is the most commonly used enzyme for H2O2 detection because it can oxidize hydrogen atoms and, for example, xenobiotics in the presence of H2O2. In order to define the limit of detection (LOD) of H2O2 we made calibrations with guaiacol and amplex red (AR), which are hydrogen donors of HRP. The accumulation of the reaction products, tetraguaiacol, and resorufin, respectively, then can be easily detected by absorption or emission (fluorescence) spectroscopy. In our experiments an enzyme electrode was fabricated from ITO (indium tin oxide), functionalized multiwalled carbon nanotubes (f-MWCNTs), and HRP. Although the enzyme activity was smaller by about two orders of magnitude when the enzyme was bound to the f-MWCNTs (ca. 10−2 M H2O2/(M HRP·sec) compared to ca. 2 M H2O2/(M HRP·sec) and 5 M H2O2/(M HRP·sec) with AR and guaiacol in buffer solution), LOD of the H2O2 decomposition was about 6 pM H2O2/sec and 10 pM H2O2/sec in the case of AR and guaiacol, respectively