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Celiac disease (CD), one of the most common food intolerances worldwide, is characterized by small intestinal mucosal injury and malabsorption in genetically predisposed individuals. CD occurs in about 1% of the population and is triggered by the ingestion of storage proteins (i.e., gluten) found in wheat, rye, barley, and possibly oats. Biochemical studies on the structures of CD-toxic proteins and peptides and the genetic, molecular, and cellular mechanisms of CD have increased our understanding of CD pathogenesis considerably during the last two decades. Due to their high Gln and Pro contents, all CD-toxic proteins are resistant to complete proteolytic digestion by gastrointestinal enzymes. Consequently, large Pro- and Gln-rich peptides accumulate in the small intestine, reach the subepithelial lymphatic tissue, and induce two different immune responses in those with CD: a rapid innate response and slower adaptive response. Both responses result in mucosal destruction and epithelial apoptosis. Stimulat...

Circular dichroism and scanning probe microscopy were used to characterize the interaction of DNA with the nonhistone chromatin protein HMGB1 and its recombinant version HMGB1(A+B) devoid of the C-terminal acidic region. The AFM data corroborate the earlier suggestion concerning the action of tandem DNA-binding domains, and support a modulatory role of the C-terminal domain in HMG protein-DNA interactions.

The infrared absorption (IR) and vibrational circular dichroism (VCD) spectra are reported for six self-complementary deoxyoctanucleotides complexed withtheanthracyclinedrugdaunomycin.The oligomers included d(CGCGCGCG)� d(CGCGCGCG), d(CGCATGCG)� d(CGCATGCG) and d(CGCTAGCG)� d(CGCTAGCG), which possess a 5 0 CGC triplet, and d(CGATATCG)� d(CGATATCG), d(CGTATACG)� d(CGTATACG) and d(CGAATTCG) � d(CGAATTCG), which have either 5 0 CGA or 5 0 CGT triplets. The latter three triplets were said to be favorable intercalation sites for this drug, while the former threewere considered to be non-preferred. Changes in the VCD spectra upon drug binding indicate a perturbation of the structure at the base step involving cytosine (Cy) and guanine (Gu), which appears to comprise the daunomycin intercalation site. The VCD spectra also show distinct changes as the drug binds with base sequences that contain 5 0 CGC triplets compared to those with either 5 0 CGA or 5 0 CGT triplets. These differences are attributed to specific binding interactions of the DNA components with the functional groups of the aglycone

Summary Background In coeliac disease, wheat, barley and rye are traditionally excluded in the gluten-free diet. However, few studies have examined the small intestinal immune response to barley and rye. Aim To investigate the immunogenicity of barley and rye prolamins (hordein and secalin respectively) in comparison with wheat gliadin. Methods Duodenal biopsies from 22 coeliac patients and 23 disease controls were cultured for 4 h with gliadin, hordein or secalin and compared with culture medium alone. Proinflammatory cytokines, interferon-γ and interleukin-2, were quantified by TaqMan polymerase chain reaction and enzyme-linked immunosorbent assay. Results Hordein caused the greatest increase in interferon-γ mRNA in coeliac patients (median: 3.3-fold) in comparison with control subjects (median: 0.28-fold, P

Celiac disease is caused by sensitivity to wheat gluten in genetically susceptible individuals. The etiological role of the other wheat-related cereals, barley, rye, and oats, is still debated. In order to investigate this issue further, in this study we examined the immune response of celiac mucosal T cell lines to fractions from all four cereals. Cell stimulation was assessed by measuring proliferation (employing (3)H-thymidine incorporation) or cytokine (IL-2, IFN-gamma) production. All five T cell lines demonstrated immunoreactivity to protein fractions from the four related cereals. In some cell lines, reactivity to wheat, barley, and rye was only evident when these cereal fractions had been pretreated with tissue transglutaminase. This study confirms the similar T cell antigenic reactivity of these four related cereals and has implications for their exclusion in the gluten-free diet. However, despite oats stimulation of T cell lines, this cereal does not activate a mucosal lesion in most celiac patients.

The four-stranded intercalated DNA structure exemplified by the oligonucleotide 5′-d(CCCCCCCCCCCC) (d(C) 12 ) was studied at acidic pH by infrared absorption (IR) and vibrational circular dichroism (VCD) spectroscopy and compared with spectra of the same oligonucleotide at neutral pH to establish distinct VCD markers for the intercalation motif. The most striking feature is a new absorption at 1694 cm − 1 and its corresponding VCD couplet with reversed sign. These are unique for the intercalated structure and have not been observed for other parallel stranded duplexes. Significant characteristic features resulting from the spatial arrangement of the sugar-phosphate backbone are also clearly present for d(C) 12 at acidic pH. An extensive network of CH…O bonds twists the backbone such that multiple through-space vibrational coupling occurs among neighbouring sugar-phosphate residues resulting in unusual VCD signals.

The analysis of absorption and circular dichroism spectra in UV and IR regions showed that Ca2+ ions interact with the phosphate groups of DNA and the HMGB1 protein. Not only the negatively charged C-terminal part of the protein molecule, but also its DNA-binding domains participate in the interaction with metal ions. The latter leads to a change in the mode of protein–DNA interaction. The presence of Ca2+ ions prevents the formation of ordered supramolecular structures specific for the HMGB1–DNA complexes but promotes intermolecular aggregation. The structure of DNA complexes with the HMGB1 protein lacking the C-terminal tail appeared to be the most sensitive to the presence of Ca2+ ions. These data indicate that Ca2+ ions play no structural role in the HMGB1–DNA complexes, and their presence is not necessary for DNA compaction in such systems.

For some applications in surgical implants a rough surface is desired, since the jagged surface structure assists the adhesion of bone material or surface coatings. Some implants are peened with coarse and sharp edged peening media. In order to avoid a distinct loss of fatigue strength, spherical peening balls should be used. The present paper shows for stainless steel X2CrNiMo18-15-3 that the effect of surface roughening can be compensated by the effect of compressive residual stresses in the surface layer. However, the effect of surface flaws must not be ignored. For this reason, the shape and depth of surface flaws in shot peened surfaces has been examined and a classification of different types of surface flaws is presented. Fatigue tests in laboratory air and in physiological NaCl solution showed that there is a distinct influence of the depth and shape of surface flaws on the fatigue strength. The use of coarser peening balls and a subsequent electrolytic polishing treatment leads to an increase of fatigue strength. Furthermore, it is shown that shot peening may have a positive or negative effect on corrosion fatigue strength.

The interaction of DNA with Mn2+ was studied in absorbance and optical activity in the electronic and vibrational regions. Based on the data, several stages of the interaction were identified. Con formational transition towards the C-form of DNA was observed in solution at the molar ratio Mn2+/DNA-phosphates between 0.1 and 1.5. The exact ratio depended on the ionic strength and increased with increasing NaCl concentration. Although manganese interacted with the phosphates and bases of DNA at higher metal concentrations, it is unlikely that direct chelation occurred. A model for the interaction between manganese ions and DNA mediated by water is suggested destabilizing the double helix and partially breaking the hydrogen bonds between the base pairs. At high Mn2+ concentrations DNA aggregation was observed.

The effects of manganese (II), nickel (II), chromium (III), and platinum (II) (cisplatin) on the double helical structure of selected oligonucleotides and DNA as detected by vibrational circular dichroism spectroscopy (VCD) are reviewed. For (dG– dC)20, the VCD spectra displayed unambiguously the transition from the normal right-handed B-form to the left-handed Z-from at the highest concentration of Mn 2þ (8.5 [Mn]/[P]). For poly(rU)·poly(rA)·poly(rU), the double-triplesingle helix transition induced by nickel (II) was clearly observable at increasing temperatures. For calf thymus DNA, chromium (III) at 0.6 [Cr]/[P] produced a 4-fold increase of the main VCD couplets, which are characterized as c-type spectra. These unusual features are due to condensed particles with dimensions comparable to the wavelength of the probing light and with regular arrangements of DNA double-helices inside the aggregates. c-Type spectra were also observed for DNA with manganese (II) between 55 and 60 8C at 2.4 [Mn]/[P]. Between 2.4 and 10 [Mn]/[P], intense and indistinct VCD features appeared above the DNA melting point indicating aggregation induced by Mn 2þ ions at elevated temperature in a relatively wide range of experimental conditions, whereas DNA condensation with Mn 2þ ions occurs only in a very narrow range of concentration and temperature. The complexes formed by coordination of cisplatin with d(CCTGGTCC)·d(GGACCAGG) and d(CCTCTGGTCTCC)·d(GGAGACCAGAGG) yielded very detailed VCD spectra, which distinctly confirmed the G p 4pG p 5 and G p 6pG p 7 lesion sites, respectively. The octamer slowly isomerized to form other adducts, which was not the case

Multichip mechatronic power packages have been developed in Motorola for automotive applications. Copper heat sink based metal substrates were used to improve thermal and electrical performance. In the early stage of development, mold delamination and die cracking have been observed after assembly. With some mold compound materials, die backside have large delaminated areas, while with other mold compound, delamination stops early but die cracks. Finite element analysis, incorporated with interface fracture mechanics method, has been conducted to understand these phenomena. Impact of mold material properties and package geometry on post-assembly delamination has been evaluated. Good agreements have been obtained between experimental data and the simulation results. The phenomenon of crack branching into the die was also studied. Finite element simulation can be used to predict whether and when the crack at the interface will turn and crack the die. With a thorough understanding of the failure mechanism, both mold delamination and die cracks have been eliminated in the final package development.

The vibrational circular dichroism (VCD) and IR absorption spectra of a dodecamer d(CCTCTGGTCTCC)·d(GGAGACCAGAGG) coordinated with cisplatin are distinct compared to those of the dodecamer without cisplatin. Although the intensity of PO2/deoxyribose absorptions (1150–850 cm−1) increases noticeably relative to those of the carbonyl and ring deformations of the bases (1750–1500 cm−1), the VCD spectra differ to a much greater extent. Overlapping positive and negative bands can be assigned relatively easily to individual vibrational modes. The effect of platination on the dodecamer duplex is expressed most prominently in VCD arising solely from the vibrations of the guanines bound to the platinum atom. The effect on the VCD features of other bases leads to minute wavenumber shifts at most. These observations are in agreement with previous NMR and X-ray experiments on the same oligonucleotide. The assignment of the absorption and VCD bands strongly resembles those of the octamer duplex d(CCTGGTCC)·d(GGACCAGG) when coordinated with platinum. The spectra of the dodecamer did not indicate any isomerization of the complex with time, as is clearly the case for the octamer. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 490–499, 2003

Background: It is well established that the wheat protein gliadin triggers inflammation in coeliac patients. However, the potential toxicity of avenin, the equivalent protein in oats, is debated. Aim: To investigate the immunogenicity of avenin using the cytokines interferon γ (IFN-γ) and interleukin (IL)-2 as markers of immunological activity. Methods: Duodenal biopsies from coeliac patients were cultured with 5 mg/ml of peptic tryptic (PT) gliadin (n=9) or 5 mg/ml of PT avenin (n=8) for four hours. Biopsies cultured with RPMI 1640 alone served as controls. Non-coeliac biopsies were also cultured with PT gliadin (n=8) and PT avenin (n=8). Total RNA was extracted from the tissue after culture. Cytokine mRNA was quantified by TaqMan polymerase chain reaction. Secreted cytokine protein was measured in the culture supernatant by enzyme linked immunosorbent assay. Results: After culture with PT gliadin, an increase in IFN-γ mRNA was observed in all nine patients with coeliac disease. Increased IFN-γ protein was also found in four of these patients. Smaller increases in IL-2 mRNA were detected in six subjects with increased IL-2 protein found in two patients. In contrast with PT gliadin, there was no significant IFN-γ or IL-2 response when coeliac biopsies were cultured with PT avenin. Similarly, biopsies from normal controls did not respond to PT gliadin or PT avenin stimulation. Conclusions: The findings of this study suggest that the immunogenic sequences in gliadin are not present in avenin. Moreover, they are in keeping with in vivo studies which report that oats are safe for consumption by coeliac patients.

Vibrational circular dichroism (VCD) spectroscopy and simultaneous IR absorption measurements are applied to study the interaction of natural calf thymus DNA with Cu 2 ions at room temperature in a Cu 2 concentration range of 0 - 0.4M (a Cu 2 /phosphate molar ratio (Cu)/(P) of 0 - 0.7). In some important instances, VCD provides more detailed insights than previous IR investigations whereas in several others it leads to the same interpretations. The Cu 2 ions bind to phosphate groups at a low metal concentration. Upon increasing the ion concentration, chelates are formed in which Cu 2 binds to the N7 of guanine (G) and a phosphate group. Detectable only by VCD, significant distortion of most guanine-cytosine (GC) base pairs occurs at a (Cu)/(P) ratio of 0.5 with only a minor affect on adenine-thymine (AT) base pairs, which favors a "sandwich" complex in which a Cu 2 ion is inserted between two adjacent guanines in a GpG sequence. The AT base pairs become significantly distorted when the metal concentration is increased to 0.7 (Cu)/(P). A number of GC base pairs, which are possibly involved in sandwich complexes, remain stacked and paired even at 0.7 (Cu)/(P), preventing complete strand separation. The DNA secondary structure changes considerably from the standard B-form geometry at a (Cu)/(P) ratio of 0.4 and higher. A further transition to some intermediate conformation that is inconsistent with either the A- or Z-form or a completely denatured state is suggested in agreement with other works. In general, VCD proves to be a reliable indicator of the 3-dimensional structure of the DNA-metal ion complexes, which reveals structural details that cannot be deduced from the IR absorption spectra alone. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 374 -390, 2003

Laser desorption/ionization (LDI) mass spectrometry suffers from poor reproducibility and a strong bias in representing the chemical composition of the sample in the mass spectra. In regard to develop laser mass spectrometry towards a quantitative analysis technique desorption and ionization processes should be separated. Here we describe a time-of-flight mass spectrometer (TOF-MS) with laser ablation and subsequent electron impact ionization (LA-EI-MS). Sample material is ablated by an Nd-YAG laser pulse (λ=355 nm, E=0.5–35 mJ, τ=9 ns), which produces ions and neutrals in the ablation plume. After expansion, parts of the plume enter the EI ion source where neutrals are ionized by electron impact (Eel=70 eV). Ions are extracted from the ion source into the flight tube of the TOF-MS by applying a pulsed repeller potential. Depending on delay times between laser pulse and repeller pulse either neutrals or ions emitted from the sample were analyzed. Different mass spectra of the same sample are obtained in t...

Phase transitions were studied of the sodium salt of poly(rA).poly(rU) induced by elevated temperature without Ni(2+) and with Ni(2+) in 0.07 M concentration in D(2)O (approximately 0.4 [Ni]/[P]). The temperature was varied from 20 degrees C to 90 degrees C. The double-stranded conformation of poly(rA).poly(rU) was observed at room temperature (20 degrees C-23 degrees C) with and without Ni(2+) ions. In the absence of Ni(2+) ions, partial double- to triple-strand transition of poly(rA).poly(rU) occurred at 58 degrees C, whereas only single- stranded molecules existed at 70 degrees C. While poly(rU) did not display significant helical structure, poly(rA) still maintained some helicity at this temperature. Ni(2+) ions significantly stabilized the triple-helical structure. The temperature range of the stable triple-helix was between 45 degrees C and 70 degrees C with maximum stability around 53 degrees C. Triple- to single-stranded transition of poly(rA).poly(rU) occurred around 72 degrees C with loss of base stacking in single-stranded molecules. Stacked or aggregated structures of poly(rA) formed around 86 degrees C. Hysteresis took place in the presence of Ni(2+) during the reverse transition from the triple-stranded to the double-stranded form upon cooling. Reverse Hoogsteen type of hydrogen-bonding of the third strand in the triplex was suggested to be the most probable model for the triple-helical structure. VCD spectroscopy demonstrated significant advantages over infrared absorption or the related electronic CD spectroscopy.

Experiments were conducted to confirm and quantify earlier observations that unbaited funnel traps in conjunction with pheromone baited funnel traps may substantially increase trap catches of Douglas-fir beetles, Dendroctonus pseudotsugae. In 12 replicates of one of these experiments during 1998 and 1999, the catches of a single baited control trap were compared to those of a set of four traps where the central trap was baited and a ring of three traps, 1 m from the central trap arranged in a star configuration, were unbaited. In the second experiment conducted during 1999, a ring of three unbaited traps was placed at 2 m and a second at 5 m from the central baited trap. Statistically robust results demonstrated clearly that the configuration of one central baited trap plus three unbaited satellite traps collected twice as many beetles on average over the season compared to the baited control trap. Addition of a second ring of unbaited traps increased collections by only about 20%, but this experiment indicated that trap catches dropped off exponentially with distance from the centre. The number of beetles caught in the baited traps was essentially the same in all 3 arrangements, suggesting that the additional unbaited traps captured beetles that otherwise may not have been captured.

Das trage Abschaltverhalten von NH-Sicherungen (M-Effekt) wird durch einen Lotpunkt auf der Schmelzleiterplatine aus Kupfer sichergestellt. Es wurde zuerst die Wirkungsweise des derzeit verwendeten Lotes SnCd20 mittels Abschmelz-, Abschalt- und Gluhversuchen charakterisiert. Im Anschluss daran wurden die alternativen Lotsysteme Zinn-Indium, Zinn-Wismut, Zinn-Wismut-Kupfer und Zinn-Indium-Kupfer untersucht. Die Legierung SnBiCu15-1 stellte sich dabei als einfuhrbare Alternative zum toxischen Lot SnCd20 dar. Verhalten und Wirkungsweise der untersuchten Lote beim M-Effekt werden beschrieben. On the mechanism of solders during the M-effect Slaggish switching-off behaviour of HBC-fusions (M-effect) is ensured by a solder droplet on the copper fusion conductor. First the function of currently used toxic SnCd20 solder was investigated by melting, switching off and annealing tests. With these results the mechanism of the “M-effect” was described and further tests were made with alternative alloys tin-bismuth, tin-indium and ternary alloys tin-bismuth-copper and tin-indium-copper. The ternary system tin-bismuth-copper was found to give best results and showed the same time-temperature-dissolution-behaviour during the M-effect as the SnCd20 solder. Function of different solders and necessary properties are discussed.

A round robin test for determination of critical pitting temperature (CPT) according to ASTM G48 produced unsatisfactory repeatability and reproducibility of results in agreement with literature. Investigations on experimental procedure, identification of pits and gravimetric evaluation of samples have been performed to identify crucial parameters for improvement of results. Several recommendations within ASTM G48 practice are proposed such as wet grinding of specimens, cold drying of specimens, additional gravimetric evaluation and optical evaluation only by skilled persons. A further suggestion is a finer ground surface of samples. In order to confer statistical reference to CPT values an evaluation of medians with 50% probability of pitting is proposed.

Vibrational circular dichroism (VCD) spectroscopy was applied to polymeric systems, in particular to several synthetic chiral polymers and DNA oligomers. After outlining the beginnings of VCD in general and as applied to the targeted systems, the two topics are discussed using examples from our laboratory. A generally optimistic conclusion is reached at the end, tempered by realization of inherent shortcomings and remaining difficulties.

Vibrational circular dichroism (VCD) spectra are reported for d(GC)20·d(GC)20 and d(ATGCATGCAT)·d(ATGCATGCAT) in D2O without Mn2+ and in the presence of 0.64 and 0.50 [Mn]/[P] concentration ratios, respectively. Changes in the VCD spectra are compared with the changes of the corresponding infrared absorption bands and interpreted in terms of structural changes in the oligonucleotides. Based on these examples, it appears that VCD provides better definition of structural modification as a result of complexation with Mn2+ ions than infrared absorption.

SDS−PAGE-separated high Mr wheat glutenin subunits stained positively in the DIG-glycan procedure, suggesting that they were glycosylated, but control experiments indicated that these were probably...

The vibrational circular dichroism (VCD) spectra of 2,5-dioxabicyclo[2.2.1]heptane-3,6-dione 1 (R = H) and the 1,4-dialkyl derivatives, 1 (R = Me) and 1 (R = t-Bu), were calculated by the ab initio magnetic field perturbation (MFP) procedure with a B3LYP/6-31G* force field, and the VCD spectra of the dimethyl and di-t-butyl derivatives were measured in the region 800-1500 cm-1. While the absolute configurations of 1 (R = Me) and 1 (R = t-Bu) could be assigned unambiguously by comparison of the experimental and predicted spectra, there is little obvious correspondence between the spectra of the series of compounds. The VCD spectra are analysed on the basis of operation of a coupled oscillator mechanism involving motions of the polar bonds. In the case of the parent dihydro system, bridgehead C-H bond motions appear to dominate contributions to the VCD of vibrational transitions into which they are mixed.Key words: vibrational circular dichroism (VCD), 2,5-dioxabicyclo[2.2.1]heptane-3,6-dione, dilactones, optical activity.

An alternate procedure for calculating vibrational circular dichroism is proposed. The method eliminates the need to solve the magnetically perturbed SCF equations which leads to an overall decrease in computer time. Instead, an expansion over electronic excited states is partially used to estimate the molecular response to the magnetic field and nuclear displacements. A rigid orbital approximation is used for the electronic states. The rotational strengths obtained in this manner are compared to original experimental data for camphor and α-pinene, and previous calculations on propylene oxide and oxirane. In all cases good agreement of simulated spectral intensities with experiment is observed. Although extensive approximations had to be adopted in the current implementation, the excitation scheme yields results superior to those obtained by the classical MFP or VCT formulations of VCD for camphor and α-pinene, whereas MFP/GIAO theory performs better in the case of oxirane.

Ab initio density functional theory (DFT) is used to predict the vibrational absorption and circular dichroism spectra of the insect pheromone 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane: frontalin. Excellent agreement with experimental spectra is obtained for the structure in which the six-membered ring is in a chair conformation and the seven-membered ring is in a boat conformation. Vibrational circular dichroism (VCD) intensities, predicted on the basis of the previously determined absolute configuration, are in excellent agreement with experiment. We conclude that VCD spectroscopy, in combination with ab initio DFT, is now an efficient tool for determining the absolute configuration and/or conformation of chiral organic molecules, including pheromones.

1-Methyl-2-cyclohexen-1-ol (MCOL) was shown for the first time to occur in the frass produced by female spruce beetles, Dendroctonus rufipennis (Kirby). MCOL and 4-methylene-6,6-dimethylbicyclo[3.1.1]hept-2-ene (verbenene) were evaluated in five geographic locations for attractiveness to spruce beetles. In trapping experiments (±)- or (+)- MCOL enhanced attraction to a standard blend of α-pinene with frontalin in two Alaska locations. (+)-MCOL was attractive and (-)-MCOL inhibitory in south-central British Columbia, and (+)-, (-)- and (±)-MCOL were all weakly attractive in one of three experiments in southeastern British Columbia and northern Alberta. Verbenene was attractive only in combination with the standard blend plus MCOL in Alaska. In comparison with the standard bait, tree baits incorporating (±)- or (+)-MCOL caused higher numbers of trees to be attacked in the interior Alaska locations and (+)- MCOL had the same effect in south-central British Columbia. Density of attack on attacked trees was unaffected. (±)- or (+)-MCOL could improve the operational efficacy of tree baits in Alaska, and (+)-MCOL could be used in south-central British Columbia. Our results indicate that for wide-ranging scolytid species, operational evaluation of new semiochemicals should be regionally specific.

The structure and force field of a bridgehead aziridine, l-azabicyclo(3.l.0)hexane (ABH), have been determined by ab initio computational methods at three levels, RHF/6-31G*(0.3), MP2/6-31G*, and Becke3LYP/6- 31G*. All three methods are shown to give very similar geometries and force fields. The chiroptical properties of ABH have been investigated experimentally and theoretically in the UV region by the ab initio PCI method and in the IR region by the vibronic coupling theory as implemented in the VCT90 program. The W/CD investigation represents the fist such study on an aziridine. The lower electronic transitions of ABH, all of which occur in the vacuum-UV region, are to Rydberg states. No simple chiral rule emerges from the UV/CD study. The experimental vibrational circular dichroism spectrum displays a prominent feature which is due to wagging of the methine hydrogen and obeys a previously identified I ICH methine wagging rule. Comparison of the CEs attributable to local modes of the three-ring methylene group of ABH with analogous published data on related aziridines suggests that some of these modes may serve as indicators of N atom and skeletal absolute configurations.

The VCD spectra in the region of 1750 to 850 cm −1 of six octadeoxynucleotides consisting of systematically varying sequences of d(CGNNNNGC) 2 , where N = A, T, C, G, are reported and tentatively interpreted based on previously reported VCD spectra of related natural and synthetic polymers and oligomers. The CO and skeletal stretching vibrations of the bases exhibit features that are characteristic for base sequences and reveal details that are not apparent in the absorption spectra. Other features, notably an unassigned band near 1500 cm −1 and the PO 2 − and furanose modes near 1080 cm −1 are independent of base sequences.

This chapter reviews the redox state in flour. It then discusses redox reactions during processing and the effect of redox agents such as oxidants and reductants on wheat flour, dough and yeast-leavened bread.

The four-stranded G-quadruplex motif is a conformation frequently adopted by guanine-rich nucleic acids that plays an important role in biology, medicine, and nanotechnology. Although vibrational spectroscopy has been widely used to investigate nucleic acid structure, association of particular spectral features with the quadruplex structure has to date been ambiguous. In this work, experimental IR absorption and vibrational circular dichroism (VCD) spectra of the model quadruplex systems d(G)(8) and deoxyguanosine-5'-monophosphate (5'-dGMP) were analyzed using molecular dynamics (MD) and quantum-chemical modeling. The experimental spectra were unambiguously assigned to the quadruplex DNA arrangement, and several IR and VCD bands related to this structural motif were determined. Involvement of MD in the modeling was essential for realistic simulation of the spectra. The VCD signal was found to be more sensitive to dynamical structural variations than the IR signal. The combination of the spectroscopic techniques with multiscale simulations provides extended information about nucleic acid conformations and their dynamics.

The interest in Vibrational Circular Dichroism (VCD) has grown at a good pace during last few years. This technique provides a detailed description of progress in vibrational optical activity for determining structural properties of pharmaceuticals. Now highly advanced VCD spectrometers are available which implement the dual polarization modulation method. This article focuses on instrumental methods, unique applicabilities and capabilities, review of scientific applications such as enantiomeric purity and absolute configuration, solution conformations, pharmaceuticals, and natural products and concludes with an assessment of the instrumentation's utility, when metal ions play significant roles in biological and medicinal processes. The study finds that same metal ions significantly affect large molecular biological complexes that arise from the interactions of DNA, proteins, and medicinal drugs. Keywords: circular dichroism; polarization; Fourier transformation; X-ray crystallography; chiral molecules

The conformation and ring-puckering vibration of 2-methoxyloxetane have been studied using microwave spectroscopy and ab initio computations. The microwave spectra of the ground and first four excited states of the ring-puckering vibration have been observed in the frequency range 8–40 GHz and the rotational and quadratic centrifugal distortion constants have been determined. Vibrational energy separations have been obtained from relative intensity measurements. The electric dipole moment (in D) of the ground vibrational state has been determined from Stark effect measurements as μ a = 0.0187 (5), μ b = 1.852 (2), μ c = 0.08 (3), and μ t = 1.854 (3). The vibrational energy separations and the vibrational dependence of the rotational constants suggest that the ring-puckering vibrational has an asymmetric single minimum potential function and also gave a revised assignment of the far infrared spectrum (J. Mol. Struct. 56 (1979) 157). A combined fit to the rotational constants, vibrational energy separations and far infrared vibrational frequencies has been used to determine a reduced potential for the ring puckering vibration. The partial derivatives of the rotational constants with respect to the reduced ring-puckering coordinate show that the equilibrium conformation has the methyl group in the equatorial position. Ab initio computations of the ring-puckering potential function have been made using 6-31G * orbitals and full geometry optimization. These computations also show the molecule to have an asymmetric single minimum potential function with an equatorial equilibrium conformation.

The structures of the cis and trans invertomers of 2-methylazirdine were optimized at the RHF/6-31G*(0.3) level of theory and the composition of the equilibrium mixture was determined to be trans/cis = 0.71:0.29, in good agreement with the experimental value, 0.66:0.35. The abinitio force field was scaled and a complete assignment of the vibrational spectra of the two conformers is presented. The IR spectrum of 2-methylazirdine was recorded in the vapor phase and in solution (cyclohexane and CCl4). The predicted IR spectrum of the equilibrium mixture agrees very well with the experimental spectrum. The 6-31G*(0.3) basis set is found to provide better geometries and more uniformly scalable force fields than the conventional 6-31G* basis set. Keywords: abinitio force fields, 2-methylaziridine.

The vibrational circular dichroism (VCD) spectrum (800 to 1500 cm−1) is reported for 2-methylthietane (2MT). Fixed partial charge (FPC), atomic polar tensor (APT), and charge flow (CF) methods are used to compute the VCD spectra for both stable conformers (CH3 in the axial or equatorial orientation) for the complete range of fundamental vibrations, based on 3-21G and 6-31G* harmonic force fields. The experimental and computed absorption and VCD spectra of R-(+)-2MT are compared to the previously reported spectra of R-(−)-2-methyloxetane. The success of the APT and CF models for reproducing the dominant ring stretching IR and VCD features of that compound is rationalized by a comparison of APT and FPC intensity expressions. Further comparison of the APT and FPC calculated electric dipole moment derivatives are interpreted to suggest values for the diagonal CS and CH stretching charge flow terms for 2MT. These investigations then provide a rationale for previously reported successes of the FPC model, and permit identification of specific vibrational modes of 2MT that are amenable to FPC-VCD modeling. The previously established conformational mixture of ~30% axial and 70% equatorial is shown to be in accord with FPC-VCD predictions for the most appropriate (β-CH2 wagging) mode. Key words: vibrational circular dichroism, 2-methylthietane, fixed partial charge, atomic polar tensor, charge flow

Publisher Summary This chapter examines the corrosion-fatigue properties of surface-treated surgical implant stainless steel X2CrNiMo18-15-3. The values of ultimate tensile strength, yield strength, and elongation at failure of cold-worked steel are 1220 MPa, 950 Mpa, and 15% respectively. The pitting resistance equivalent number of the steel is 26.7, which represents a low probability for pitting in body fluids and in a physiological 0.9% NaCI solution. The surface profile of shot-peened surfaces after electrolytic polishing is irregular of the rough surface. A similar effect is observed on nonmetallic inclusions in electrolytically polished smooth surfaces. The electrolytic polishing of a shot-peened surface smoothens the sharp-edged surface flaws and results in a significant decrease of the notching effect. If the state of residual stress is only slightly influenced by the electrochemical treatment; the electrolytic polishing treatment would have a positive influence on fatigue properties. In order to achieve this positive effect, it is necessary to remove a thin surface layer ∼20 μm thick. The annealing treatment of electropolished specimens causes only a small decrease in fatigue strength. The annealing treatment after shot peening reduces the fatigue strength by 40% compared to electropolished specimens.

The microwave spectrum of 3-methyloxetane has been observed in the frequency range 12.4–40.0 GHz in order to investigate the conformational behaviour of this molecule. The spectra of the ground vibrational state, the first five excited states of the ring-puckering vibration and four other excited vibrational states have been assigned and their rotational and quartic centrifugal distortion constants have been obtained. The ring-puckering vibrational energy separations obtained from microwave relative intensity measurements do not appear to be consistent with those predicted from a ring-puckering potential function obtained from far infrared spectroscopy. A revised assignment of the far infrared spectrum gives a potential function consistent with the microwave relative intensity measurements. This potential function is preferred because of its superior ability to account for the ring-puckering vibrational dependence of the rotational and centrifugal distortion constants. Although this is a slightly asymmetric double minimum potential function, the top of the barrier lies below the lowest vibrational level and therefore in its ground vibrational state 3-methyloxetane effectively has a planar ring. The four excited states which do not belong to the ring-puckering progression based on the ground vibrational state are assigned to a ring-puckering progression based on the first excited state of the methyl torsion. The first two members of this progression show relatively large changes in their rotational constants relative to the ground vibrational state indicating a strong interaction between the ring-puckering and methyl torsion vibrations. The electric dipole moment has been determined from Stark effect measurements as μa = 1.910 (5) D, μc= 0.77 (2) D and μ = 2.06 (1) D for the ground vibrational state. The μa component and the total electric dipole moment decrease with excitation of the ring-puckering vibration.

The vibrational spectra have been measured for 2-methylthietane over the range 100–1600 cm−1 (Raman) and 400–3200 cm−1 (solution and vapour phase infrared). Abinitio calculations at the 3-21G and 6-31G* levels indicate that both the axial and equatorial conformers represent minima on the ring inversion potential surface, the latter suggesting the equatorial species to be more stable by 191 cm−1. Vibrational force fields were evaluated for each of the two conformers and scaled using factors previously optimized for thietane and 2-methyloxetane. All of the major experimental features were readily assigned to the equatorial species, and most transitions expected for the axial species were also located. Calculated absorption intensities, although not accurate in an absolute sense, proved useful in predicting the relative intensities for corresponding axial and equatorial transitions. Keywords: 2-methylthietane, vibrational spectra, abinitio force fields, vibrational assignment, conformations.

The interactions were studied of DNA with the nonhistone chromatin protein HMGB1 and histone H1 in the presence of manganese(II) ions at different protein to DNA and manganese to DNA phosphate ratios by using absorption and optical activity spectroscopy in the electronic [ultraviolet (UV) and electronic circular dichroism ECD)] and vibrational [infrared (IR) and vibrational circular dichroism (VCD)] regions. In the presence of Mn2+, the protein–DNA interactions differ from those without the ions and cause prominent DNA compaction and formation of large intermolecular complexes. At the same time, the presence of HMGB1 and H1 also changed the mode of interaction of Mn2+ with DNA, which now takes place mostly in the major groove of DNA involving N7(G), whereas interactions between Mn2+ and DNA phosphate groups are weakened by histone molecules. Considerable interactions were also detected of Mn2+ ions with aspartic and glutamic amino acid residues of the proteins. © 2006 Wiley Periodicals, Inc. Biopolymers 83: 182–192, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

The vibrational circular dichroism (VCD) and infrared absorption (IR) spectra of the mismatched octamer oligonucleotides d(CGTGCGCG)2 (CGT) and d(CGCGTGCG)2 (CGC) and their complexes with the antitumor drug daunomycin were measured in D2O, interpreted, and compared to the octamer d(CGCGCGCG)2 (CG). The IR spectra of the mismatched octamers in the carbonyl-stretching region are similar to those of the parent CG, whereas the VCD spectra differ in several respects between each other. The main VCD feature due to carbonyl stretching is informative for the mismatches and CG. Vibrational modes in the sugar–phosphate region remain essentially unchanged especially for PO2− symmetric stretching. Differences between the free and complexed mismatch octamers occurred mainly in the carbonyl-stretching region (1700–1600 cm−1). The absorption intensity of the CO peak of G is more prominent for CGC than CGT and resembles CG in this respect. The detailed composition of this doublet is clearly visible, indicating the geometric rearrangement of the base pairs in the presence of the mismatch and upon forming the daunomycin complex. © 2005 Wiley Periodicals, Inc. Biopolymers 82: 189–198, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

In this work we have studied ligand-induced secondary structure changes in the small calcium regulatory protein calmodulin (CaM) using vibrational circular dichroism (VCD) spectroscopy. We find that, due to its chiral sensitivity, VCD spectroscopy has increased ability over IR spectroscopy to detect changes in the structure and flexibility of secondary structure elements upon ligand binding. Moreover, we demonstrate that the uniform isotope labeling of CaM with 13C shifts its amide I′ VCD band by about ∼43 cm–1 to lower wavenumbers, which opens up a spectral window to simultaneously visualize a bound target protein. Therefore this study also provides the first example of how isotope labeling enables protein–protein interactions to be studied by VCD with good separation of the signals for both isotope-labeled and unlabeled proteins. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 231–237, 2005 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

The analysis of absorption and circular dichroism spectra in UV and IR regions showed that Ca2+ ions interact both with the phosphate groups of DNA and with the HMGB1 protein. Not only negatively charged C-terminal part of the protein molecule participates in interaction with metal ions but also its DNA-binding domains. The latter fact leads to the change of the mode of protein-DNA interaction. The presence of Ca2+ ions prevents formation of ordered supramolecular structures, specific for the HMGB1-DNA complexes, though promotes intermolecular aggregation. The structure of the complexes between DNA and the protein HMGB1 lacking C-terminal tail appears to be the most sensitive to the presence of Ca2+ ions. The data obtained allow to conclude that Ca2+ ions do not play a structural role in the HMGB1/DNA complexes and the presence of these ions is not necessary to DNA compaction in such systems.

The vibrational circular dichroism (VCD) and IR absorption spectra of a dodecamer d(CCTCTGGTCTCC).d(GGAGACCAGAGG) coordinated with cisplatin are distinct compared to those of the dodecamer without cisplatin. Although the intensity of PO(2)/deoxyribose absorptions (1150-850 cm(-1)) increases noticeably relative to those of the carbonyl and ring deformations of the bases (1750-1500 cm(-1)), the VCD spectra differ to a much greater extent. Overlapping positive and negative bands can be assigned relatively easily to individual vibrational modes. The effect of platination on the dodecamer duplex is expressed most prominently in VCD arising solely from the vibrations of the guanines bound to the platinum atom. The effect on the VCD features of other bases leads to minute wavenumber shifts at most. These observations are in agreement with previous NMR and X-ray experiments on the same oligonucleotide. The assignment of the absorption and VCD bands strongly resembles those of the octamer duplex d(CCTGGTCC).d(GGACCAGG) when coordinated with platinum. The spectra of the dodecamer did not indicate any isomerization of the complex with time, as is clearly the case for the octamer.