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Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy has been used to investigate the effect of weak electromagnetic fields on the structure of L-glutamine (L-Gln) and L-phenylalnine (L-Phe) in aqueous solution. It has been found that the exposure to a DC field or a 50 Hz AC field, for a short time induces modifications in the spectra of exposed samples in agreement with our preceding observations on glutamic acid. Furthermore, the acid–base equilibrium has been investigated by using the ratio of the intensity of the deprotonated on protonated species. In the case of L-Phe, the exposure induces a measurable shift of acid dissociation constant pKa1 out of the experimental errors, while in case of L-Gln, the effect is under the limit detectable with this method. The phenomenon of the shift of the acid–base equilibrium has been connected elsewhere to modification of the water–water hydrogen bonds in the water around both the backbone and the residue (R). Here we suggest that the magnetic field modifies the water structure around the molecules and changes the hydrophobic interactions allowing the molecules of amino acids to aggregate. The differences observed in the behavior of L-Phe and L-Gln may be related to the differences in the polarity of their residues. Bioelectromagnetics. 35:129–135, 2014. © 2013 Wiley Periodicals, Inc.

Ultrasound (US) induced enhancement of plasma membrane permeability is a hugely promising tool for delivering exogenous vectors at the specific biological site in a safe and efficient way. In this respect, here we report effects of membrane permeability alteration on fibroblast-like cells undergoing very low-intensity of US. The change in permeability was pointed out in terms of high uptake efficiency of the fluoroprobe calcein, thus resembling internalization of small cell-impermeable model drugs, as measured by fluorescence microscopy and flow cytometry. Fluorescence evidences moreover suggests that the higher the time of exposure, the larger will be the size of molecules can be internalized. The uptake events were related to the cell viability and also with structural changes occurring at membrane level as revealed by infrared spectroscopy and preliminary membrane fluidity and atomic force microscopy (AFM) investigation. Thus, the question of whether the uptake of cell-impermeable molecules is consistent with the presence of disruptions on the cell membrane (sonopore formation) has been addressed. In this framework, our findings may constitute experimental evidence in support of sub-cavitation sonoporation models recently proposed, and they may also provide some hints towards the actual working condition of medical US dealing with the optimum risk to benefit therapeutic ratio.

Although medical ultrasound offers compelling opportunities to improve therapy in principle, progress in the field has been limited because of an insufficient understanding of the potential genotoxic and cytotoxic effects of ultrasound on biological systems. This paper is mainly focused on an in vitro study of effects with respect to genotoxicity and viability induced by 1- and 3-MHz medical ultrasound in murine fibroblasts (NIH-3T3) at low-intensity exposure (spatial peak temporal average intensity Ita

IR spectra of mixtures of light and heavy water seem to provide a clear evidence for the existence of substructures, each of which may be assigned to a particular kind of water molecule on the basis of their correlation with the local environment. These substructures have been related to three different populations named correlated, non correlated and intermediate according to their degree of correlation. Experimental data analysis show that, in a mixture of H2O-D2O, each population participates differently to the solution process.

The reaction of bovine serum albumin (BSA) with [ trans-RuCl 4(Im)(dimethylsulfoxide)][ImH] (Im = imidazole) (NAMI-A), an experimental ruthenium(III) anticancer drug, and the formation of the respective NAMI-A/BSA adduct were investigated by X-ray absorption spectroscopy (XAS) at the sulfur and chlorine K-edges and at the ruthenium K- and L 3-edges. Ruthenium K and L 3-edge spectra proved unambiguously that the ruthenium center remains in the oxidation state +3 after protein binding. Comparative analysis of the chlorine K-edge XAS spectra of NAMI-A and NAMI-A/BSA, revealed that the chlorine environment is greatly perturbed upon protein binding. Only modest changes were observed in the sulfur K-edge spectra that are dominated by several protein sulfur groups. Overall, valuable information on the nature of this metallodrug/protein adduct and on the mechanism of its formation was gained; XAS spectroscopy turns out to be a very suitable method for the characterization of this kind of systems.

In this study we modified and optimized a technique using an ordinary spin-coater device to deposit lipids on chemically etched silicon substrates. Tapping-mode atomic force microscopy is used for sample characterization, thereby realizing non destructive characterization with nanometrical resolution.

The main purpose of this work is to investigate the possibility of utilizing both a classical biological method to test cytotoxicity and a physical measurement procedure as the FT-IR spectroscopy to study the interaction between cells lines and heavy metals. Jurkart, a lymphocyte cell line, was treated with cadmium chloride, cadmium oxide and the organic germanium compound named Ge-oxy-132. The utilized value of heavy metal concentration allows us to obtain significant results with both methods and with all metals. In fact by using lower values of concentration any effect is revealed after treatment with germanium. The results of the simultaneous measurements by both experimental procedures are here reported for the first time and show that, while the cytotoxic effects of the two cadmium compounds are confirmed, the organic germanium compound reveals a very different and interesting interaction with Jurkart cells. The behaviour of the Jurkart cells upon the uptake of cadmium or organic germanium is very different: while treatment with CdO and CdCl(2) determines proteins denaturation and lipids oxidation in cells until the death, these processes are not revealed after Ge-oxy-132 treatment.

This work is focused on the in vitro study of the effects induced by medical ultrasound (US) in murine fibroblast cells (NIH-3T3) at a low-intensity of exposure (spatial peak temporal average intensity Ita

The Fe site structure in the recombinant wild-type and T72I mutant of the cooperative homodimeric hemoglobin (HbI) of the mollusc Scapharca inaequivalvis has been investigated by measuring the Fe K-edge X-ray absorption near edge structure (XANES) spectra of their oxy, deoxy and carbonmonoxy derivatives, and the cryogenic photoproducts of the carbonmonoxy derivatives at T=12 K. According to our results, the Fe site geometry in T72I HbI-CO is quite similar to that of human carbonmonoxy hemoglobin (HbA-CO), while in native HbI-CO it seems intermediate between that of HbA-CO and sperm whale MbCO. The XANES spectra of oxy and deoxy derivatives are similar to the homologous spectra of human HbA, except for T72I HbI, for which the absorption edge is blue-shifted (about +1 eV) towards the spectrum of the oxy form. XANES spectra of the cryogenic photoproducts of HbA-CO (HbA*), HbI-CO (HbI*) and mutant HbI-CO (T72I HbI*) were acquired under continuous illumination at 12 K. The Fe-heme structures of the three photoproducts are similar; however, while in the case of HbA* and HbI* the data indicate incomplete structural relaxation of the Fe-heme towards its deoxy-like (T) form, the relaxation in T72I HbI* is almost completely towards the proposed "high affinity" Fe-heme structure of T72I HbI. This evidence suggests that minor tertiary restraints affect the Fe-heme dynamics of T72I HbI, corresponding to a reduction of the energy necessary for the T→R structural transition, which can contribute to the observed dramatic enhancement in oxygen affinity of this hemoprotein, and the decreased cooperativity.

The effect of allosteric effectors, such as inositol hexakisphosphate and/or bezafibrate, has been investigated on the unliganded human adult hemoglobin both spectroscopically (employing electronic absorption, circular dichroism, resonance Raman, and x-ray absorption near-edge spectroscopies) and functionally (following the kinetics of the first CO binding step up to a final 4% ligand saturation degree). All data indicate that the unliganded T-state is not perturbed by the interaction with either one or both effectors, suggesting that their functional influence is only exerted when a ligand molecule is bound to the heme. This is confirmed by the observation that CO dissociation from partially liganded hemoglobin ( Y ¯ ≤ 0.04) is strongly altered by the presence of either effector, and the effect is enhanced whenever the two effectors are simultaneously present. Altogether, these data are a direct demonstration of the occurrence of a strain induced by the presence of a ligand molecule bound to the heme, and for the first time there is a clear indication that the expression of the functional heterotropic effect by these non-heme ligands requires this strain, which is not present in the unliganded molecule.

Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy has been used to investigate the effect of weak electromagnetic fields on the structure of L-glutamine (L-Gln) and L-phenylalnine (L-Phe) in aqueous solution. It has been found that the exposure to a DC field or a 50 Hz AC field, for a short time induces modifications in the spectra of exposed samples in agreement with our preceding observations on glutamic acid. Furthermore, the acid-base equilibrium has been investigated by using the ratio of the intensity of the deprotonated on protonated species. In the case of L-Phe, the exposure induces a measurable shift of acid dissociation constant pKa1 out of the experimental errors, while in case of L-Gln, the effect is under the limit detectable with this method. The phenomenon of the shift of the acid-base equilibrium has been connected elsewhere to modification of the water-water hydrogen bonds in the water around both the backbone and the residue (R). Here we suggest that the magnetic field modifies the water structure around the molecules and changes the hydrophobic interactions allowing the molecules of amino acids to aggregate. The differences observed in the behavior of L-Phe and L-Gln may be related to the differences in the polarity of their residues.

For the first time a comparative study on conformational differences between native oval­ buminand its heat-stable form, called S-ovalbumin. using small angle x-ray scattering, is reported. To detect a different pathway in the folding mechanism of the two proteins, scatter­ing measurements have been performed on ovalbumin and S-ovalbumin denatured with dif­ferent concentrations of guanidine hydrochloride, and by heating the proteins at acid pH. The intensity scattering curves provide evidence that the intermediate states in the unfolding process are globular for both proteins while their compactness changes. The reported experi­mental results suggest that the ovalbumin to S-ovalbumin transformation can be considered a protein-switch triggered by changes in the chemical conditions of the protein environment. Because the conformational changes are likely to be of functional importance, we infer that the occurrence in vivo of S-ovalbumin is thus determined by the transformation of ovalbumin, with a functional role for embryonic development, into a new protein with a dif­ferent function.

Ultrasound effects on biological samples are gaining a growing interest concerning in particular, the intracellular delivery of drugs and genes in a safe and in a efficient way. Future progress in this field will require a better understanding of how ultrasound and acoustic cavitation affect the biological system properties. The morphological changes of cells due to ultrasound (US) exposure have been extensively studied, while little attention has been given to the cells structural changes. We have exposed two different cell lines to 1 MHz frequency ultrasound currently used in therapy, Jurkat T-lymphocytes and NIH-3T3 fibroblasts, both employed as models respectively in the apoptosis and in the gene therapy studies. The Fourier Transform Infrared (FTIR) Spectroscopy was used as probe to reveal the structural changes in particular molecular groups belonging to the main biological systems. The genotoxic damage of cells exposed to ultrasound was ascertained by the Cytokinesis-Block Micronucleus (CBMN) assay. The FTIR spectroscopy results, combined with multivariate statistical analysis, regarding all cellular components (lipids, proteins, nucleic acids) of the two cell lines, show that Jurkat cells are more sensitive to therapeutic ultrasound in the lipid and protein regions, whereas the NIH-3T3 cells are more sensitive in the nucleic acids region; a meaningful genotoxic effect is present in both cell lines only for long sonication times while in the Jurkat cells also a significant cytotoxic effect is revealed for long times of exposure to ultrasound.

Fourier transform infrared spectroscopy in attenuated total reflection can be used to discriminate the necrotic from the apoptotic cell death in a tumoral T cell line irradiated by a UV source able to induce both apoptosis and necrosis. Using Jurkat cells as the model system, significant spectral differences in the irradiated cells vs. time were observed in the lipid-proteins ratio absorbance band at 1,397 cm(-1) and in lactic acid IR band at 1,122 cm(-1); these spectral features are inversely correlated with the percentage of apoptotic cells assessed by flow cytometry. From the analysis of second derivatives in the IR spectral region between 1,800 and 900 cm(-1), we have detected two significant spectral changes: the first centered at 1,621 cm(-1) by analyzing the components of the amide I band and the second centered at 1,069 cm(-1) due to C-O stretching vibration of the DNA backbone sensitive to the dehydrated state of DNA; these identified differences in the intracellular biomolecules have been allowed to monitor the necrotic process. The variations in the spectral data set have been identified by the Kruskal-Wallis test and confirmed by the hierarchical cluster analysis.

The experiment was performed to prove that exposure to a relatively weak extremely low frequency (ELF) magnetic field retards tadpoles' development.Two cohorts of Xenopus laevis laevis (Daudin) tadpoles were exposed during their immature period ( approximately 60 days) to a 50 Hz magnetic field of 63.9or = Bor = 76.4 microT rms (root mean square, average values) magnetic flux density in a solenoid. At the same time, as controls, two comparable cohorts were reared in two aquariums remote from the solenoid. Cohorts' degree of development was quantified by daily inspections of animal limbs and attributing them to a stage of the Nieuwkoop and Faber ( 1956 ) classification. The experiment was replicated three times.(a) Mean developmental rate of exposed cohorts was reduced with respect to controls (0.43 vs. 0.48 stages/day, p0.001) starting from early larval stages; (b) Exposure increased the mean metamorphosis period of tadpoles by 2.4 days compared with the controls (p0.001); (c) Maturation rates of exposed and control tadpoles changed during maturation period; and (d) Important mortality, malformations or teratogenic effects were not observed in exposed matured tadpoles.A long-term exposure of X. laevis tadpoles to a relatively weak 50 Hz magnetic field causes a sub-lethal effect that slows down their larval developmental rate and delays their metamorphosis.

The polarized Cu K-edge X-ray Absorption Near Edge Structure (XANES) of La2CuO4 has been interpreted by the multiple scattering approach. The size of the cluster of neighbouring atoms having good agreement with the XANES experimental data is determined by 45 atoms surrounding the absorbing Cu. The polarized spectra can be predicted in term of a one-electron dipole (Δl=+1) transition Cu 1s→ϵp, probing the unoccupied p-like (l=1) density of states projected on a Cu site with orbital angular momentum ml=0 in the E∥z spectra, and the ml=1 for the E⊤c spectra. Thus we show that the electronic structure of the high energy conduction bands, beyond the Cu 3d band, of La2CuO4 are well described in terms of the one-electron approximation. It is shown that XANES spectra are consistent with the contraction of the Cu-apex oxygen distance with doping. Final state effects induced by the core hole have been indentified: (i) the core transitions take place in the fully relaxed potential, (ii) the satellite at 7 eV above the main K-XANES peak in both polarizations is assigned to a multielectron shake up excitation. Finally the shoulder on the rising absorption edge, present in many Cu compounds and usually assigned to a shake down multi-electron excitation, is shown to be due to a one-electron transition to a state delocalized over a large cluster.

The reactive oxygen species (ROS) produced inside cells by UV-B radiation may induce apoptosis, a process that realizes the programmed death of cells. In the present paper the UV induced damage was studied in a human T-Lymphocyte cell line (the Jurkat line) by mean of IR laser photoacoustic spectroscopy (PAS) and by Fourier Transform Infrared Spectroscopy (FTIR) combined with biological assays based on flow cytometry. The apoptosis was induced in vitro in the Jurkat samples by exposition to UV-B radiation with a dose of 310 mJ/cm2. PAS measurements were performed through a 10W c.w. CO2 laser based optical system realised at ENEA Molecular Spectroscopy Laboratory in Frascati (Italy).© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Pozzi, D., Grimaldi, P., Gaudenzi, S., Di Giambattista, L., Silvestri, I., Morrone, S. and Congiu Castellano, A. UVB-Radiation-Induced Apoptosis in Jurkat Cells: A Coordinated Fourier Transform Infrared Spectroscopy-Flow Cytometry Study. Radiat. Res. 168, 698–705 (2007). We studied the induction of apoptosis in Jurkat cells by UVB radiation (wavelength 290–320 nm) at a dose of 310 mJ/ cm2. We combined Fourier transform infrared (FTIR) spectroscopy with flow cytometry to determine whether the combination of both techniques could provide new and improved information about cell modifications. To do this, we looked for correspondences and correlations between spectroscopy and flow cytometry data and found three highly probable spectroscopic markers of apoptosis. The behavior of the wave number shift of both the Amide I β-sheet component and the area of the 1083 cm−1 band reproduced, with a high correlation, the behavior of the early apoptotic cell population, while the behavior of the Amide I area sh...

We investigated, by FTIR microspectroscopy, the interaction of some cationic and helper lipids with DNA deposited on solid supports allowing the formation of ordered structures. FTIR experiments were performed using both conventional and synchrotron radiation infrared sources and by depositing the lipids on both silicon and wedged diamond plates. Cationic liposomes composed of DOTAP (1,2-dioleoyl-3-trimethylammonium–propane) or DDAB (dimethyldioctadecylammonium bromide) and one helper neutral lipid DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) at different cationic lipid/DNA weight ratio, were studied. Spectra of the single components are compared with those obtained for both equimolar cationic–neutral mixture and lipid/DNA complexes.

The effect of serum on structural properties of dimethyl-dioctadecyl-ammonium bromide (DDAB)-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposomes and DDAB-DOPE/DNA lipoplexes has been investigated by energy dispersive X-ray diffraction (EDXD) technique, at different cationic lipid/DNA weight ratios (rho). The role of serum on the size of lipoplexes has also been studied by dynamic light scattering. Lipoplex transfection efficiency (TE) as a function of rho, and lipoplex toxicity to C6 rat glioma cells have been evaluated in Dulbecco's Modified Eagle Medium (DMEM) with and without serum. A multi-parametric analysis concerning the role of size, structure and cytotoxicity on transfection efficiency contributes to explain the experimental observation that 3beta-[N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol)-DOPE/DNA transfect C6 cells better than DDAB-DOPE/DNA lipoplexes.

Paper is the main component of a huge quantity of cultural heritage. It is primarily composed of cellulose that undergoes significant degradation with the passage of time. By using small angle neutron scattering (SANS), we investigated cellulose's supramolecular structure, which allows access to degradation agents, in ancient and modern samples. For the first time, SANS data were interpreted in terms of water-filled pores, with their sizes increasing from 1.61 nm up to 1.97 nm in natural and artificially aged papers. The protective effect of gelatine sizing was also observed.

We used Fourier Transform Infrared Spectroscopy (FTIR) combined with flow cytometry to study the apoptosis and necrosis processes in Jurkat, a lymphocyte cell line. The apoptosis was induced in the cells by a chemical agent, the actinomycin D, while the necrosis was induced lowering the pH value to 4.2. The apoptotic events were analysed by flow cytometry (using annexin V and propidium iodide) and contemporary monitored by FTIR spectroscopy at different times after the treatment. This comparison allowed us to find in the IR spectrum, between 3000 cm−1and 2800 cm−1, a “marker band” of the apoptosis corresponding to the exposure of phosphatidylserine on the outer leaflet of the membrane. A marker of a specific cellular process obtained by using a non‒destructive technique such as FTIR spectroscopy, has a great significance in the diagnostic medicine providing a tool for detecting pathologiesin vivo.

We present a study of x-ray synchrotron radiation and neutron reflectivity on solid-supported lipid membranes prepared by spin coating. This technique has the advantage of allowing the control of the number of lipid layers by varying the deposition parameters. The experiments were performed on the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane chloride salt (DOTAP), the neutral lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), the lipid mixture (DOTAP-DOPC), and the complex (DOTAP-DOPC∕DNA) deposited on wafers. Only single neutral lipids or lipid-peptide mixtures were deposited on solid substrate using the spin coating technique and characterized. Results on the structure of the deposited lipid layers indicate that DNA contributes to the order in the lipoplexes.

We used atomic force/lateral force microscopy (AFM/LFM) and the transfer of a lipophilic fluorescent dye (octadecylrhodamine G, R 1 8 ) to study the morphology and fusion of human prostasomes at pH values ranging between 5and 8. The AFM data revealed that the mean diameter of untreated prostasomal vesicles was about 200 nm, but a second prostasome population with a diameter of about 400 nm is also present. This second population increased upon exposing the vesicles to low pH values. The AFM/LFM characterization revealed the smoothness of the prostasome surface and showed that the larger vesicles were fused prostasomes, as also indicated by the relief of R 1 8 self-quenching.

Visible light can break the Fe—CO bond in Fe(II) carbonmonoxy-myoglobin (MbCO) giving an unligated product (Mb*) that is almost stable at T < 30 K. Fe K-edge polarized X-ray absorption spectra (P-XAS) of the photoproduct (T = 20 K) of an oriented single crystal (0.2 × 0.2 × 0.3 mm) of sperm whale MbCO (space group P21) have been collected. By rotating the crystal the X-ray photon polarization vector has been oriented almost parallel (with an angle α = 23°) or perpendicular (α = 86°) to the heme normal of each myoglobin molecule. The crystal was continuously illuminated by a white-light source during the data collection. The polarized data give novel information on the Fe-heme electronic/structural rearrangement following photolysis. The XANES (X-ray absorption near-edge structure) spectrum polarized in the direction close to the Fe—CO bond changes dramatically after photolysis, exhibiting a shift of ∼2 eV, due to electronic relaxation of empty states of pz symmetry, while more subtle changes are observed in the spectrum polarized along the heme plane, sensitive to the heme-plane geometry. Changes in the pre-edge region can be interpreted to provide insight into the electronic structure of the highest occupied and lowest unoccupied molecular orbitals (HOMO–LUMO) in the MbCO → Mb* photochemical reaction at low temperature.

We found, by circular dichroism and Raman spectroscopy measurements, that the secondary structure of the native ovalbumin and of its heat-stable form, called S-ovalbumin, is a probe of the structural differences between the two proteins. Small angle X-ray scattering and circular dichroism measurements performed on the two proteins under denaturing conditions, with different concentrations of guanidine hydrochloride, show the changes of the tertiary and secondary structure and a different pathway in the unfolding process. These experimental data confirm that the conversion of native ovalbumin into S-ovalbumin is irreversible and reveal that the response of the two proteins to the same chemical environment is different

We have measured the x-ray absorption near edge structure (XANES) spectra of the enzyme tyrosinase from the mushroom Agaricus bisporus in solution in the oxy and deoxy forms. The spectra, obtained under the same conditions as the analogous forms of mollusc hemocyanin (Hc), show that the oxidation state of copper changes from Cu(II) (oxy form) to Cu(I) (deoxy form), and the copper active site(s) of A. bisporus tyrosinase in solution undergoes the same main conformational changes as Hc. We have applied the multiple scattering theory to simulate the XANES spectra of various alternative geometries of the copper site, accounting for the residual differences between Hc and tyrosinase. While oxy-Hc is reasonably fitted only by the pseudo-square-pyramidal geometry reported by its crystallographic data, oxytyrosinase can be fitted, starting from the Hc coordinates, either by distortions toward a pseudo-tetrahedral geometry, with inequivalent copper sites, or by an apically distorted square-pyramidal geometry (with an elongation of the apical distance of no more than 0.2 A).

We report experimental evidence that the pH value of the micro-environment of the protein is the key for the conformational changes of transferrin, rather than the ligated or unligated state of the binding sites. The "open" and "closed" conformation of protein, suggested by X-ray crystallography in static condition, is triggered by the pH value and the effect is independent of the metal ion being transported. We propose a simple description of the structure-function relationship that allows this protein to deliver, in particular, iron or aluminum ions in the biological cycle.

X-ray small angle scattering experiments, using a pin hole SAXS camera with Synchrotron radiation source, have been performed to study the conformational changes of lyophilized samples of Apo-, Mono-, and Diferric- human transferrin. We report the experimental evidence that the analysis of the scattered intensity through the fractal theory may give information on the particle size and its variation upon iron binding.

The changes of the Fe heme-active site conformation of dromedary (Camelus dromedarius) nitrosylhemoglobin (HbNO) induced by inositol hexakisphosphate (IHP) and chlofibric acid (CFA) have been studied by using X-ray absorption near-edge structure (XANES) spectroscopy. Structural information has been determined by multiple scattering analysis of the Fe K-edge XANES spectra. The proximal histidine is found to move away from iron centers by about 0.4 Angstrom on the average over the four hemes upon binding of CFA or stoichiometric amount of IHP. In molar excess of polyanion or in the simultaneous presence of IHP, CFA and chloride, the proximal histidine moves back to a position very close to that observed in pure buffer; yet, the structure modulation induced by the allosteric effectors is not completely reversible. Such findings parallel with the functional properties and the spectroscopic (e.g., EPR and absorbance) characteristics of HbNO.

Differences in the local structure of the heme in the isolated alpha-, beta- and gamma-chains of the adult and fetal human hemoglobin are detected by XANES (X-ray absorption near-edge structure) spectroscopy. The ligand bonding angle to the iron ion in the ligated forms and the displacement of the Fe respect to the porphyrin plane in the deoxy forms are found to be different for each chain.

Size distribution of dimyristoylphosphatidylcholine liposome suspensions was investigated by dynamic-light scattering (DLS) as a function of the sonication time (ts). Cumulant expansion (second- and third-order) and regularized Laplace inversion (CONTIN) of dynamic single-angle laser light-scattering data were performed. With both methods, the intensity-weighted mean hydrodynamic radius 〈r〉I depended on the investigated lengthscale. The number-weighted mean hydrodynamic radius (〈r〉N), obtained from CONTIN by modeling dimyristoylphosphatidylcholine vesicles as thin-walled hollow spheres, resulted as independent on the lengthscale. However, the 〈r〉N value obtained from cumulant expansions remained lengthscale-dependent. Therefore, the number-weighted radius distribution function is highly asymmetric. The number-weighted mean radius, the standard deviation, and the number-weighted radius at the peak \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}(r_{{\mathrm{N}}}^{{\mathrm{peak}}})\end{equation*}\end{document} all decreased to a plateau when increasing sonication time. At ts longer than 1 h, the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}r_{{\mathrm{N}}}^{{\mathrm{peak}}}\end{equation*}\end{document} compares well with the radius of unilamellar vesicles in equilibrium with monomers predicted on a thermodynamic basis. The reliability of our analysis is proved by the comparison of experimental Rayleigh ratios with simulated ones, using the normalized number-weighted radius distribution function pN(r) determined by DLS data. A perfect agreement was obtained at longer sonication times, and the average aggregation number was determined. At lower ts values, simulations did not match experimental data, and this discrepancy was ascribed to the presence of large and floppy unilamellar vesicles with ellipsoidal shapes. Our investigation shows that, from single-angle DLS data, the radius distribution function of the vesicles can only be obtained if pN(r) is known.

This book the second volume in the "Springer Series in Biophysics" col lects together contributions to the conference on "Biophysics and Syn chrotron Radiation" held in July 86 at Frascati. This meeting addressed the advances on the structure of biological molecules obtained by using synchrotron radiation. In fact it was most timely to review the results of the research in biophysics which is rapidly developing at synchrotron radiation facilities. Moreover, there was interest to discuss the new perspectives opened up by the future high brilliance synchrotron radia tion sources. With the use of synchrotron radiation, x-ray spectroscopy of biological molecules is firmly established in the techniques of EXAFS and XANES. Contributions to the detailed knowledge of local structure of active sites of metalloproteins by this approach are presented in this volume, together with a number of studies of -the interaction of metal ions with other important biological macromolecular systems. Structural determination of very large biological systems at high reso lution, including a protein and its substrate, are reported. The experi mental advances in protein crystallography presented here reduce the time for solving protein structures, thus satisfying a major require ment of the rapidly-expanding field of protein engineering."

SummaryThe inner structure of fibrin fibres grown from fibrinogen solution activated by human α-thrombin was investigated by means of an Energy Dispersive X-ray Diffraction technique. The experiments show evidence for the well-characterized 22.5 nm repeat distance, which indicates the high order of protofibril arrangement in the longitudinal direction of fibres. The diffraction pattern also manifested a further pronounced peak at 18.1 nm (and its second order reflection at 18.1/√2) demonstrating the existence in fibrin of a high degree of lateral order. The reported results directly confirm, on unperturbed wet samples, that protofibrils closely associate giving rise to a crystalline axial and equatorial packing according to the conclusions of the multibundle model.Theme paper: Part of this work was originally presented at the joint meetings of the 16th International Congress of the International Society of Fibrinolysis and Proteolysis (ISFP) and the 17th International Fibrinogen Workshop of the International Fibrinogen Research Society (IFRS) held in Munich, Germany, September, 2002.

By use of X-ray absorption near-edge structure (XANES), circular dichroism, and visible absorption spectroscopies, dromedary carbonmonoxyhemoglobin has been characterized structurally and functionally. By consideration of the experimental results the following view emerges: (i) the quaternary structure is not the unique factor determining the tertiary environment around the heme, and (ii) the multiplicity of interactions between hemoglobin and solvent components induces a large number of globin conformations, which somehow affect the conformation of the heme such that the structural parameters (i.e., the doming of porphyrins, the movements of the iron relative to the heme plane, the distortion of the ligand field, and the change in the Fe-C-O angle) can be uncoupled.