The emerging structural genomics initiatives provide novel opportunities to complement the rapidly increasing amount of genomic sequence data with the three-dimensional molecular structures of the coded genes. Many of these gene products exert their cellular functions by interacting with multiple partners. Unravelling the molecular structures of these interactions provides the most useful information to investigate their involvement in cellular processes. To this end, the determination of structures exceeds the number of coded gene products by several orders of magnitude. Structural genomics offers opportunities to synergise European research in structural biology technologies, with a multitude of excellent centres currently available. In this contribution, current initiatives of the Hamburg Outstation of the European Molecular Biology Laboratory will be outlined.
The Cu(II) and Fe(III) ions have been adsorbed by four potato starches of different degrees of oxidation (different numbers of COOH groups replacing host CH_2OH groups): native (no oxidized), white (pudding) with oxidation degree of 0.04%, gelating (0.1%), and LUBOX starch (0.5%). Concentration of the ions in starches was determined from atomic absorption and EPR spectrum intensity. For small concentration of the adsorbed ions (below 4 mg/g) nearly all ions are adsorbed from the solution. EPR shows that adsorbed copper(II) ions are chemically bonded to the starch molecules (preferably) at COOH sites and uniformly dispersed in the starch structure. The complexes are typical of octahedral or square-quadratic coordination with spin-Hamiltonian parameters g_ǁ=2.373, g_⊥= 2.080, A_ǁ=12.1 mT, A_⊥=1.0 mT. For higher concentrations the Cu(II) displays a tendency to clustering. Iron(III) ions are introduced into starch in a form of clusters mainly, even for the smallest concentration. The highest concentrations of both Cu(II) and Fe(III) were observed in LUBOX starch having the highest degree of oxidation.
A nuclear magnetic resonance spin-lattice relaxation dispersion study of the relaxation of several magnetization components in both natural and deuterated lysozyme solutions was undertaken at 20°C. Proton and deuteron resonances were employed. The two-dimensional time evolution of the magnetization and the spin-spin relaxation were analyzed. In addition, an isotopic dilution study was performed at 5 and 30.6MHz. The results indicate that the water proton spin-lattice relaxation rate which arises from intermolecular relaxation between the water protons and the lysozyme protons represents a relatively strong relaxation mechanism. A model for the dynamics of the water molecules, consistent with the proton and deuteron dispersions as well as with the isotopic dilution results, is presented.
Micro-Raman spectroscopy was used to studies of naturally occurring biogenic ferritin, synthetic ferritin with magnetic core (magnetoferritin) as well as their several mimetics. We demonstrate the ability of micro-Raman spectroscopy to discriminate between ferritin and magnetoferritin used in the studies. The results are promising for further use of the Raman spectroscopy as potential tool to distinguish between the forms of iron present in biogenic materials and biological tissues.
Hybrid nanostructures are often composed of inorganic parts and "biological" ones. Optimized through million years of evolution light harvesting proteins are hard to mimic synthetically. Promising strategy in search for efficient solar cells is an attachment of selected natural protein systems to inorganic quantum dots. Such experimental hybrid structures should have improved charge separation properties. Among the most promising proteins is peridinin-chlorophyll-protein from Amphidinium carterae (PCP). It has a wide absorption spectrum (420-550 nm), optimized for sunlight. The dynamics of this protein, used in modern nanotechnology has been not addressed yet. In this work we present results of PCP computer modeling using a well established molecular dynamics methodology. The CHARMM27 force field parameters were prepared for this protein and all chromophore components. The system was embedded in a box of water, with proper counter ions, and a number of 10 ns molecular dynamics simulations were run using the NAMD code. It has been found that peridinine chromophores exhibit substantial orientational flexibility but a pair Per612 and Per613 is more rigid than the remaining two carotenoids. Orientation and dynamics of absorption and emission electric dipole moments have been also analyzed. Apparently, the architecture of PCP is not optimized for efficient Per-Chl a energy transfer by the Förster mechanism. Several practical issues related to molecular dynamics simulation of similar hybrid nanostructures are discussed.
The aim of this work was to compare free radical properties of some model neuromelanins obtained from dopamine and its mixture with 5-S-cysteinyldopamine in various molar ratios. The EPR method was used in these investigations; the samples were detected at X and K bands. The parameters of EPR spectra, free radicals concentrations in air and in vacuum, the influence of microwave power and temperature on intensity of resonance signals were measured.
Magnetic optical rotatory dispersion (MORD) of thin selected biological tissues and thin film of composite made from akaganeite mineral and PVA as well as ferritin and their mimetics aqueous suspensions were performed in spectral range 250-650 nm at room temperature. Good correlation between MORD spectra for akaganeite composite film, ferritin and their mimetics aqueous suspensions with spectra of thin slices of human tissue obtained from white matter of the brain and spleen were observed. Comparison suggest a contribution from Fe(III) to MORD spectra of tissues. This preliminary results show that application of MORD spectroscopy to clinical analysis may be useful.
Magnetically induced optical birefringence (Δ n) was measured for magnetoferritin and horse spleen ferritin aqueous suspensions. The Δ n for magnetoferritin was described in the frame of the Langevin formalism taking into account distribution of core diameter. The established average magnetic dipole moment and core diameter is equal to about 460 μ_{B} and 3 nm, respectively. It was shown that magnetic birefringence and the Cotton-Mouton constant can be powerful parameters in identification of the magnetic core structure of ferritin, especially useful in biomedicine.
Many proteins in alive organisms have a domain structure providing them the possibility to reversible unfolding, which seems to play an essential role in those processes occurring in tissues which are controlled by mechanical cellular tension. In this work the atomic force microscopy was applied to investigate the mechanical properties of the single molecules of fibronectin, a protein participating in the important mechanical processes in extracellular matrix. The results showed that the conditions of mechanical stretching influence not only the force required to unfolding of a domain but also the increase in protein contour length induced by such unfolding event. Two mean values of the increase in length (called shortly the unfolding length) L_1 and L_2, were obtained and ascribed to unfolding of either the whole fibronectin domain of type III (L_2) or its fragment (L_1). Both unfolding lengths revealed similar dependence on the stretching conditions. This experimental observation of increase in unfolding length with increasing loading rate was successfully described with a combination of two theoretical models (Bell model and the worm-like-chain model), previously used separately in the analysis of protein unfolding. The general mechanical property of fibronectin domains was emphasized and proposed as a potential determinant of the cellular adhesion.
The complementarity of synchrotron derived ultrahigh resolution X-ray and neutron protein crystallography is explored via an ensemble of plant lectin concanavalin A crystal structures. Thus a resume of a study of a cryo 0.94Å and a neutron (+X-ray) protein crystal 2.4Å structure at room temperature is made and these are then compared in their efficiency to determine the positions of the bound solvent atoms i.e. as hydrogens or deuteriums. First results are also presented of comparisons of two ultrahigh resolution protein crystal structures, the 0.94Å and a new 0.92Å structure. Thus the variability of the two cryo structures, at very fine detail, is described; this variability is in the multiple occupancies of side chains. Overall, one can see that a "complete" structure definition, with today's experimental capabilities, is possible and can include structure ensemble variations.
The words of braid closures for the pretzel knots, in particular the twist knots relevant to molecular supercoils in biochemistry, are recorded in a standardized form, which enables one to see the regular pattern of the words, and thus to write the braid words representing pretzel knots for general values of the crossing number.
Biomolecular recognition is an open scientific problem, which has been investigated in many theoretical and experimental aspects. In that sense, there are encouraging results within Resonant Recognition Model (RRM), based on the finding that there is a significant correlation between spectra of the numerical presentation of amino acids in the primary structure of proteins and their biological activity. It has been found through an extensive research that proteins with the same biological function have a common frequency in their numerical spectra. This frequency was found then to be a characteristic feature for protein biological function or interaction The RRM model proposes that the selectivity of protein interactions is based on resonant energy transfer between interacting biomolecules and that this energy, electromagnetic in its nature, is in the frequency range of 10^{13} to 10^{15} Hz, which incorporates infra-red (IR), visible and a small portion of the ultra-violet (UV) radiation. In this paper, the quantum mechanical basis of the RRM model will be investigated using the solution in the simplified framework of Hückel-like theory of molecular orbits.
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.