The optimization of the reaction conditions (pH, T, t) to obtain stable copper(II) ion complexes with dextran derivatives were investigated in this paper. A complete synthesis of stable aqueous complexes can be realized with reduced low-molar polysaccharides, at an average molar mass 5000 g mol–1 and pH 7.5–8. Fourier-transform IR spectra of polysaccharide dextran and its compounds with copper(II) ion, recorded at room temperature, were analyzed in order to obtain the information about the structure and the conformation of these polymer compounds. The ESR parameters of the spectra indicate the square-planar coordination of Cu(II) ion with four O atoms. Copper(II) complex formation with dextran and its derivatives were analyzed by physicochemical methods. Synthesized complexes of Cu(II) ion with reduced low-molar dextran in comparison with commercial preparations showed the considerably lower acute toxicity (LD50 1705).

Milorad Caki&#x107;

&#x17d;arko Miti&#x107;

Goran S. Nikoli&#x107;

Ljubomir Ili&#x107;

Goran M. Nikoli&#x107;

The investigations of bioactive copper(II) complexes with reduced low-molar dextran

His93Gly sperm whale myoglobin (H93G Mb) has the proximal histidine ligand removed to create a cavity for exogenous ligand binding, making it a versatile template for the preparation of model heme complexes. In this study, we have measured the first and second ligand binding affinities of imidazole and pyridine to form mono- and bis-ligated ferric and ferrous H93G Mb complexes. Electronic absorption spectroscopy has been utilized to determine the binding affinities for the proximal (Kd1, first ligand) and distal (Kd2, second ligand) pockets of H93G Mb. Magnetic circular dichroism spectroscopy has been used to confirm the identity of the complexes. The binding affinities for the first ligand are one hundred- to one thousand-fold higher than those for the second ligand (Kd1 « Kd2) for the same exogenous ligand. This is entirely opposite to what is seen with free heme in organic solvents where Kd1 » Kd2. Thus, the proximal pocket is the high affinity binding site. The lower affinity for the distal pocket can be attributed to steric hindrance from the distal histidine. This report provides quantitative evidence for differential ligand binding affinities of the proximal and distal pockets of H93G Mb, a unique property that facilitates generation of heme iron derivatives not easily prepared with other heme model systems.

Jing Du

Masanori Sono

John H. Dawson

The proximal and distal pockets of the H93G myoglobin cavity mutant bind identical ligands with different affinities: Quantitative analysis of imidazole and pyridine binding

Modern spectroscopic techniques are highly useful in studying diverse processes in microbial cells related to or incited by environmental factors. Spectroscopic data for whole cells, supramolecular structures or isolated cellular constituents can reflect structural and/or compositional changes occurring in the course of cellular metabolic responses to the effects of pollutants, environmental conditions (stress factors); nutrients, signalling molecules (communication factors), etc. This information on the molecular level, often obtained using non-destructive techniques with minimal sample preparation, is of importance for basic studies on mechanisms of bacterial tolerance to stresses and their impact on bacterial metabolism, as well as for applied multidisciplinary research in the fields related to biotechnology, bioremediation, agriculture, biogeochemistry, etc. In the present communication, some recent examples are reviewed and discussed which illustrate the applicability of Fourier transform infrared (FTIR) spectroscopy for monitoring metabolic changes in soil bacteria, using the examples of intensively studied plant-growth-promoting rhizobacteria of the genus Azospirillum. Compositional and structural changes occurring in whole bacterial cells in response to different stress factors and plant signals, as well as spectroscopic images of relevant biospecific interactions are considered from the viewpoint of the possibilities provided by this versatile and easy-to-use technique and its methodology.

Alexander A. Kamnev

FTIR spectroscopic studies of bacterial cellular responses to environmental factors, plant-bacterial interactions and signalling

Raman and infrared spectroscopy are optical spectroscopic techniques that use light scattering (Raman) and light absorption (infrared) to probe the vibrational energy levels of molecules in tissue samples. Using these techniques, one can gain an insight into the biochemical composition of cells and tissues by looking at the spectra produced and comparing them with spectra obtained from standards such as proteins, nucleic acids, lipids and carbohydrates. As a result of optical spectroscopy being able to measure these biochemical changes, diagnosis of cancer could take place faster than current diagnostic methods, assisting and offering pathologists and cytologists a novel technology in cancer screening and diagnosis.The purpose of this study is to use both spectroscopic techniques, in combination with multivariate statistical analysis tools, to analyze some of the major biochemical and morphological changes taking place during carcinogenesis and metastasis in lymph nodes and to develop a predictive model to correctly differentiate cancerous from benign lymph nodes taken from oesophageal cancer patients.The results of this study showed that Raman and infrared spectroscopy managed to correctly differentiate between cancerous and benign oesophageal lymph nodes with a training performance greater than 94% using principal component analysis (PCA)-fed linear discriminant analysis (LDA). Cancerous nodes had higher nucleic acid but lower lipid and carbohydrate content compared to benign nodes which is indicative of increased cell proliferation and loss of differentiation.With better understanding of the molecular mechanisms of carcinogenesis and metastasis together with use of multivariate statistical analysis tools, these spectroscopic studies will provide a platform for future development of real-time (in surgery) non-invasive diagnostic tools in medical research.

M. Isabelle

N. Stone

H. Barr

M. Vipond

N. Shepherd

K. Rogers

Lymph node pathology using optical spectroscopy in cancer diagnostics

Curcumin is the main constituent of curry. In its ground state it shows chemo-preventive, chemo-therapeutic and anti-inflammatory effects. For its immunostimulating action it has been considered for the development of drugs suitable for treating AIDS and cystic fibrosis. Further biological action is induced in curcumin by photoactivation: in suitable environmental conditions electronically excited curcumin can act as a singlet oxygen generator. Moreover, cytotoxicity is enhanced by light exposure and antibacterial effects are photosensitized. This work is aimed to understand the photobiological action of curcumin by elucidating the deactivation mechanisms of its first excited singlet state. In particular we find evidence of the role of tautomerization in the excited state by measuring fluorescence lifetimes and quantum yields for such compound dissolved in solvents of different polarity and H-bonding capability. Degradation quantum yield and singlet oxygen generation efficiency were also measured in acetonitrile and methanol. The results emphasize the strong dependence of the deactivation processes from the environment. The deactivation phenomenology can be fully explained by postulating intramolecular proton transfer in the cis enol conformer to be the leading non-radiative deactivation pathway.

Luca Nardo

Roberta Paderno

Alessandra Andreoni

Már Másson

Tone Haukvik

Hanne Hjorth TØnnesen

Role of H-bond formation in the photoreactivity of curcumin

This review discusses the contribution of time-resolved infrared spectroscopy to the understanding of the Ca2+ pump in the sarcoplasmic reticulum membrane of skeletal muscle cells (SERCA1a). The focus is on interactions of the substrate ATP with the ATPase and on the bond parameters of the phosphoenzyme phosphate group. Functional groups throughout the ATP molecule are important for stabilising the closed conformation of the ATP–ATPase complex and for fast phosphorylation of the ATPase. Dissociation of the reaction product ADP after phosphorylation leads to a more open average conformation of the enzyme and does not trigger the transition from the first phosphoenzyme Ca2E1P to the second E2P. The P–O bond between phosphate and aspartyl moieties is weaker in Ca2E1P and E2P than in acetyl phosphate in aqueous solution, which explains the high reactivity of the phosphoenzymes. This ground state property of the phosphoenzymes prepares for a phosphate transfer reaction with dissociative character.

Andreas Barth

Structural dynamics of the Ca2+-ATPase studied by time-resolved infrared spectroscopy

Thermally stimulated depolarization currents technique has been employed to investigate the conformation of hen egg white lysozyme in native and amyloid form, in the state of powder at very low hydration level. The technique, able to detect the current generated by thermally activated reorientation of water dipoles previously oriented by an electric field, exploits H2O dipoles, belonging to the solvation shell, as a probe to gain information on the protein conformation.Large differences are detected between the TSDC spectra related to the two different protein conformations, for what concerns the number and position of the main peaks, the native form displaying two peaks, at TM=175 K and at TM=297 K, and the amyloid one, only one at intermediate temperature (TM=235 K). The spectra have been compared with those monitored for poly-L-lysine (MW 80400), as received and prepared in different ways, i.e. α-helix, β-sheet, and coil conformation, respectively. The poly-L-lysine spectra show specific features that can be attributed to water texture around the secondary structure adopted by the macromolecule: the results stress how TSDC technique is a tool of great potential value in the conformational analysis of proteins.

Maria Grazia Bridelli

Rosanna Capelletti

Hydration structure analysis of lysozyme amyloid fibrils by thermally stimulated depolarization currents (TSDC) technique

Differences between Raman spectra of normal, malignant and benign tissues have been recorded and analyzed as a method for the early detection of cancer. To the best of our knowledge, this is one of the most statistically reliable research (67 patients) on Raman spectroscopy-based diagnosis of breast cancers among the world women population. The paper demonstrates that Raman spectroscopy is a promising new tool for real-time diagnosis of tissue abnormalities.

H. Abramczyk

I. Placek

B. Brozek-Pluska

K. Kurczewski

Z. Morawiec

M. Tazbir

Human breast tissue cancer diagnosis by Raman spectroscopy

The influence of lysopalmitoylphosphatidylcholine (Lyso-PPC) on lamellar dispersions of dipalmitoylphosphatidylcholine (DPPC) has been investigated by spectrophotometry and electron spin resonance (ESR) of spin-labelled phosphatidylcholine at the C-5 or at the C-16 positions in the sn-2 acyl chain (5- and 16-PCSL). On increasing the concentration of Lyso-PPC up to 10 mol%, the spectral anisotropy of 5-PCSL is slightly reduced whereas that of 16-PCSL is markedly increased. This effect of the lysolipid on the DPPC lipid chain mobility is evident from 10 to 50 mol% at low temperature in the gel phase, disappears in the fluid phase, is associated with the lack of the pre-transition in the mixed lipid dispersions and it is interpreted as interdigitation of the DPPC lipid chains. At intermediate concentrations and for temperatures in the gel phase, the ESR spectra of both labels in DPPC and Lyso-PPC mixtures are the superposition of an anisotropic lamellar component and of an isotropic micellar signal, suggesting the coexistence of lamellar and micellar aggregates. Chain interdigitation and lamellar-micellar coexistence are not evident for temperature above the melting transition temperature. At high Lyso-PPC content (≥60 mol%) the mixed lipid dispersions reach the optical clarity, the main transition is no more detected and spin-label ESR spectra typical of micellar dispersions are detected in the whole temperature range investigated.

Manuela Pantusa

Luigi Sportelli

Rosa Bartucci

Phase behaviour of DPPC/Lyso-PPC mixtures by spin-label ESR and spectrophotometry

Infrared spectroscopy (IR) was applied to study changes in solid teeth tissues of persons exposed to low (0.12–0.20 Gy) and high (0.5–1.7 Gy) doses of ionizing radiation during their work in the Chernobyl zone after the accident. Changes in the inorganic and organic matrix of teeth were noted for both high and low radiation doses. The obtained results demonstrated that high doses of radiation lead to imbalance between phosphate–carbonate phases level (because of increasing of CO32− content) and accumulation of soluble phosphates in the mineral part of the teeth. These changes have an effect on dental matrix strength. Low doses of radiation do not induce appreciable negative changes in the mineral part of all tooth tissues but lead to changes in organic matrix of teeth (in collagen).The present results demonstrated that pathological effect of radiation touches upon all dental tissue and obviously all bone systems of irradiated people.

L. A. Darchuk

L. V. Zaverbna

V. G. Bebeshko

A. Worobiec

E. A. Stefaniak

R. Van Grieken

Infrared investigation of hard human teeth tissues exposed to various doses of ionizing radiation from the 1986 Chernobyl accident

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Journal of Spectroscopy publishes research into the theory and application of spectroscopy across all disciplines, including biology, chemistry, engineering, earth sciences, medicine, materials science, physics, and space science.

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Chief Editor&nbsp;Dr Daniel Cozzolino&nbsp;is based at the University of Queensland, Australia. His research focuses on the developments of chemometric and spectroscopic methods for use in agriculture and food applications.

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Journal of Spectroscopy publishes research into the theory and application of spectroscopy across all disciplines, including biology, chemistry, engineering, earth sciences, medicine, materials science, physics, and space science.

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