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At least 19 recordsLinked to original sources
PubMed2000

The evaluation of structural changes in wool fibre keratin treated with azo dyes by Fourier Transform Infrared Spectroscopy.

Fourier Transform Infrared Spectroscopy spectroscopy is a useful technique for the analysis of structural changes in wool fibres at the molecular and supermolecular levels. Ecological requirements the textile industry has to meet oblige manufacturers to use ecological dyes in the process of fibre dyeing. These dyes should not split into the forbidden, carcinogenic aromatic amines (e.g. benzidine) while used. Wool was dyed with an azo dye, then underwent a chemical reaction. Changes were observed in the region of Amide A, Amide B, Amide I and II, dipolar ions amino acids, and the fingerprint region.

Animals↗
PubMed1998

Discrimination among Bacillus cereus, B. mycoides and B. thuringiensis and some other species of the genus Bacillus by Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy (FTIR) in conjunction with canonical variate analysis was found to be effective in discriminating among spectra of 9 representative strains of Bacillus spp., including B. cereus, B. mycoides and B. thuringiensis. The method was also able to discriminate according to species among spectra of 14 other non-type strains of B. cereus, 12 of B. mycoides and 12 of B. thuringiensis with a success rate of > 95%, even without using a prior classification of the groups by species. FTIR spectroscopy can be used for the rapid and accurate differentiation of species in the genus Bacillus that are of importance to the food and dairy industry.

Animals↗
PubMed2003

Dietary supplement oil classification and detection of adulteration using Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy (FT-IR) methods and common chemometric techniques [including discriminant analysis (DA), Mahalanobis distances, and Cooman plots] were used to classify various types of dietary supplement oils (DSO) and less expensive, common food oils. Rapid FT-IR methods were then developed to detect adulteration of DSO with select common food oils. Spectra of 14 types of DSO and 5 types of common food oils were collected with an FT-IR equipped with a ZnSe attenuated total reflectance cell and a mercury cadmium telluride A detector. Classification of DSO and some common food oils was achieved successfully using FT-IR and chemometrics. Select DSO were adulterated (2-20% v/v) with the common food oils that had the closest Mahalanobis distance to them in a Cooman plot based on the DA analysis, and data were also analyzed using a partial least-squares (PLS) method. The detection limit for the adulteration of DSO was 2% v/v. Standard curves to determine the adulterant concentration in DSO were also obtained using PLS with correlation coefficients of >0.9. The approach of using FT-IR in combination with chemometric analyses was successful in classifying oils and detecting adulteration of DSO.

Dietary Fats, Unsaturated↗
PubMed2005

Discrimination of enterobacterial repetitive intergenic consensus PCR types of Campylobacter coli and Campylobacter jejuni by Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy (FT-IR) has been used together with pattern recognition methodology to study isolates belonging to the species Campylobacter coli and Campylobacter jejuni and to compare FT-IR typing schemes with established genomic profiles based on enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). Seventeen isolates were cultivated under standardized conditions for 2, 3, and 4 days to study variability and improve reproducibility. ERIC-PCR profiles and FT-IR spectra were obtained from strains belonging to the species Campylobacter coli and C. jejuni, normalized, and explored by hierarchical clustering and stepwise discriminant analysis. Strains could be differentiated by using mainly the first-derivative FT-IR spectral range, 1,200 to 900 cm(-1) (described as the carbohydrate region). The reproducibility index varied depending on the ages of the cultures and on the spectral ranges investigated. Classification obtained by FT-IR spectroscopy provided valuable taxonomic information and was mostly in agreement with data from the genotypic method, ERIC-PCR. The classification functions obtained from the discriminant analysis allowed the identification of 98.72% of isolates from the validation set. FT-IR can serve as a valuable tool in the classification, identification, and typing of thermophilic Campylobacter isolates, and a number of types can be differentiated by means of FT-IR spectroscopy.

Animals↗
PubMed2003

Identification of species of Brucella using Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy (FTIR) is a technique that has been used over the years in chemical analysis for the identification of substances and is one that may be applied to the characterisation of microorganisms. The marked tendency of Brucella towards variation in the smooth rough phase, together with the laboriousness and risk involved in the methods used in their identification, make their classification difficult. We studied the type strains of the different species and biovars of Brucella and 11 isolates of human origin of Brucella melitensis, six corresponding to biovar 1, one to biovar 2 and five to biovar 3. The results of linear discriminant analysis performed using the data provide an above 95% likelihood of correct classification, over half of which are in fact above 99% for the vast majority of Brucella strains. Only one case of B. melitensis biovar 1 has been incorrectly classified. The rest of the microorganisms studied (Staphylococcus aureus, Strteptococcus pyogenes, Enterococcus faecalis, Corynebacterium pseudodiphtheriticum, Clostridium perfringens, Escherichia coli, Acinetobacter calcoaceticus and Pseudomonas aeruginosa) have been classified correctly in all cases to a likelihood of over 80%. In the graphic representation of the analysis, a grouping of these can be seen in clusters, which include the different species. One of these comprises B. melitensis, another Brucella abortus, and another wider one is made up of Brucella suis. The Brucella canis, Brucella ovis and Brucella neotomae strains appear separate from the previously described groups.

Brucella↗
PubMed1997

Characterization of the secondary structure and assembly of the transmembrane domains of trypsinized Na,K-ATPase by Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy has been used to compare native Na,K-ATPase-containing membranes with those trypsinized in the presence of either Rb+ or Na+ ions to remove the extramembranous parts of the protein. The protein secondary structure content deduced from the amide I band is approximately 30-35% alpha-helix, 37-40% beta-structure, and 13-15% random coil for native membranes from shark rectal gland and from pig kidney, in both the Na- and K-forms. Trypsinization in either Rb+ (a K+ congener) or Na+ removes approximately 35% of the amide I band intensity of native membranes from shark rectal gland. The protein secondary structural content of the trypsinized membranes lies in the range of approximately 23-32% alpha-helix, 37-46% beta-structure, and 12-18% random coil for the shark and kidney enzymes. The distribution of intensity between the bands corresponding to protonated and deuterium-exchanged alpha-helices, and between the component bands attributed to beta-structure, changes considerably on trypsinization, in the direction of a greater proportion of protonated alpha-helix and a broader range of frequencies for beta-structure. The kinetics of deuteration of the slowly exchanging population of protein amide groups is also changed on trypsinization. The mean rate constant for deuteration of trypsinized membranes is approximately half that for native membranes, whereas the proportion of amides contributing to this population increases on trypsinization. The temperature dependence of the amide I band in the Fourier transform infrared spectra indicates that the onset of thermal denaturation occurs at 58 degrees C for native membranes (in either Na+ or K+) and for membranes trypsinized in Rb+, but the major denaturation event for membranes trypsinized in Na+ occurs at approximately 84 degrees C. These results correlate with the functional properties of the intramembranous section of the enzyme.

Animals↗
PubMed1992

Generation of a substructure library for the description and classification of protein secondary structure. II. Application to spectra-structure correlations in Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy has become well known as a sensitive and informative tool for studying secondary structure in proteins. Present analysis of the conformation-sensitive amide I region in protein infrared spectra, when combined with band narrowing techniques, provides more information concerning protein secondary structure than can be meaningfully interpreted. This is due in part to limited models for secondary structure. Using the algorithm described in the previous paper of this series, we have generated a library of substructures for several trypsin-like serine proteases. This library was used as a basis for spectra-structure correlations with infrared spectra in the amide I' region, for five homologous proteins for which spectra were collected. Use of the substructure library has allowed correlations not previously possible with template-based methods of protein conformational analysis.

Algorithms↗
PubMed1993

Secondary structure and temperature behavior of the acetylcholine receptor by Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy (FT-IR) was used to test the secondary structure of purified acetylcholine receptor membranes from Torpedo californica. The secondary structure was estimated using the spectral features observed in the structure sensitive region of amide I and amide I' (between 1600 and 1700 cm-1), taking advantage of Fourier self-deconvolution and second-derivative techniques along with least-squares band fitting procedures. At least six different amide I' band components could be resolved in D2O and were tentatively assigned to beta-structures (1680 and 1636 cm-1), alpha-helices (1657 cm-1), aperiodic structures and/or distorted helices (1646-1648 cm-1), and turns (1690 and 1668 cm-1), respectively. The beta-band around 1637 cm-1, in particular, turned out to be complex since it reproducibly exhibited weak features near 1630 and 1627 cm-1, thereby suggesting the presence of different chain interacting beta-structures. The band near 1657 cm-1 was assigned to alpha-helices which transverse the membrane bilayers, while 1646-1648-cm-1 component was tentatively attributed to aperiodic structures and alpha-helices localized within the "globular head" of the receptor protein protruding from the membrane surface into the surrounding water. Least-squares band fitting procedures were applied in order to estimate relative amounts of secondary structures. The results suggest 36-43%, 32-33%, 14-24%, and 18-19% for beta-, alpha-helical, turn, and "rest" structures, respectively. Additionally, the temperature- and time-dependent variations of the secondary structure was tested by evaluating the changes of amide I and amide II band components of receptor membranes dispersed in H2O and D2O.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Characterization of the pretransition in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine by Fourier transform infrared spectroscopy.

Fourier transform infrared spectroscopy has been used to study the infrared-active acyl chain vibrational modes of fully hydrated multibilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (L-DPPC) over the temperature range 0-55 degrees C. Frequencies, bandwidths, and other spectral parameters were measured as a function of temperature for the methylene scissoring, rocking, and wagging modes, as well as for the C-H stretching modes, and they were used to monitor the packing of the acyl chains. Particular emphasis was placed on determining the nature of the pretransition event. It is shown that between 36 and 38 degrees C the spectral changes are indicative of a phase change in the acyl chain packing from an orthorhombid to a hexagonal subcell. It is also concluded that in the gel phase, at all temperatures below the main transition, the acyl chains are predominantly in all-trans conformations and that the temperature-dependent variations of spectral parameters result from changes in interchain interactions.

Fourier Analysis↗
PubMed1999

Effect of calcium and phosphatidic acid binding on the C2 domain of PKC alpha as studied by Fourier transform infrared spectroscopy.

Fourier transform infrared (FTIR) spectroscopy was used to investigate the structural and thermal denaturation of the C2 domain of PKC alpha (PKC-C2) and its complexes with Ca(2+) and phosphatidic acid vesicles. The amide I regions in the original spectra of PKC-C2 in the Ca(2+)-free and Ca(2+)-bound states are both consistent with a predominantly beta-sheet secondary structure below the denaturation temperatures. Spectroscopic studies of the thermal denaturation revealed that for the PKC-C2 domain alone the secondary structure abruptly changed at 50 degrees C. While in the presence of 2 and 12.5 mM Ca(2+), the thermal stability of the protein increased to 60 and 70 degrees C, respectively. Further studies using a mutant lacking two important amino acids involved in Ca(2+) binding (PKC-C2D246/248N) demonstrated that these mutations were inherently more stable to thermal denaturation than the wild-type protein. Phosphatidic acid binding to the PKC-C2 domain was characterized, and the lipid-protein binding became Ca(2+)-independent when 100 mol% phosphatidic acid vesicles were used. The mutant lacking two Ca(2+) binding sites was also able to bind to phosphatidic acid vesicles. The effect of lipid binding on secondary structure and thermal stability was also studied. Beta-sheet was the predominant structure observed in the lipid-bound state, although the percentage represented by this structure in the total area of the amide I band significantly decreased from 60% in the lipid-free state to 47% in the lipid-bound state. This decrease in the beta-sheet component of the lipid-bound complex correlates well with the significant increase observed in the 1644 cm(-1) band which can be assigned to loops and disordered structure. Thermal stability after lipid binding was very high, and no sign of thermal denaturation was observed in the presence of lipids under the conditions that were studied.

Animals↗
PubMed2002

Chloride cofactor in the photosynthetic oxygen-evolving complex studied by fourier transform infrared spectroscopy.

Fourier transform infrared (FTIR) spectroscopy, using midfrequency S2/S1 FTIR difference spectra, has been applied to studies of chloride cofactor in the photosynthetic oxygen-evolving complex (OEC) to determine the effects of Cl(-) depletion and monovalent anion substitution. Cl(-) depletion resulted in the disappearance of a large part of the amide I and II vibrational modes, and induced characteristic modification in the features of the stretching modes of the carboxylate ligands of the Mn cluster. The normal spectral features were largely restored by replenishment of Cl(-) except for some changes in amide bands. The overall features of Br(-) -, I(-) -, or NO3(-) -substituted spectra were similar to those of the Cl(-) -reconstituted spectrum, consistent with their ability to support oxygen evolution. In contrast, the spectrum was significantly altered by the replacement of Cl(-) with F- or CH3COO(-), which resulted in marked suppression and distortion of both the carboxylate and amide bands. The activity of oxygen evolution restored by NO3(-) was as high as that by Cl(-) when measured under limited light conditions, indicating that the NO3(-) -substituted OEC is fully active in oxygen evolution, although with a slow turnover rate. The double-difference spectrum between the 14NO3(-) -substituted and 15NO3- -substituted S2/S1 difference spectrum showed isotopic bands for asymmetric NO stretching mode in the region of 1400-1300 cm(-1) due to NO3(-) bound to the Cl(-) site. This demonstrated structural coupling between the Cl(-) site and the Mn cluster. A proposed model for the isotopic bands suggested that Cl(-) as well as NO3(-) is not directly associated with the Mn cluster and exists in a more symmetric configuration and weaker binding state in the S2 state than in the S1 state. These results also suggest that Cl(-) is required for changes in the structure of the specific carboxylate ligand of the Mn cluster as well as the peptide backbone of protein matrixes upon the transition from S1 to S2.

Calcium↗
PubMed1999

[Investigation of the reaction of iso-propylamine on propylene oxide by Fourier transform infrared spectroscopy].

Fourier transform infrared spectroscopy method has been developed for in-situ monitoring the reaction of iso-propylamine on propylene oxide without the need to sample the reaction medium. The profile of the reaction and the influences of conditions can be directly reflected in the feature absorbance changes of the reactant and product at 826 cm(-1) and 1069 cm(-1), respectively. It is shown that the in situ infrared spectroscopy is a powerful technique to investigate the mechanism and kinetics of the reaction and to optimize the control conditions.

English Abstract↗
PubMedDate not supplied

Changes in protein secondary structure during gluten deformation studied by dynamic fourier transform infrared spectroscopy.

Fourier transform infrared (FT-IR) spectroscopy was used to monitor changes in the secondary structure of wheat prolamins, the main components of gluten, during mechanical deformation in a series of cycles of extension and relaxation. A sample derived from protein bodies isolated from developing grain showed a buildup of persistent beta-sheet structure. In gluten, the ratio of beta-sheet to random and beta-turn structures changed on extension. After the applied force was released, the sample recovered some of its original shape and structure, but the material became stiffer in consecutive extension cycles. The relationship between gluten structure and mechanical properties is discussed in terms of a model in which conversion of beta-turn to beta-sheet structure is a response to extension and a means by which elastic energy is stored in the system.

Glutens↗
PubMed1998

Urea denaturation of staphylococcal nuclease monitored by Fourier transform infrared spectroscopy.

Fourier transform infrared (FTIR) amide I spectroscopy has not been widely used as a method to study protein folding. Some thorough studies of thermal unfolding have been carried out; however, protein unfolding in the presence of the widely used denaturants guanidine hydrochloride and urea has only recently been reported. Guanidine hydrochloride and urea both absorb strongly in the amide I region, as does H2O. Here, we have used deuterated 13C-urea as the chemical denaturant and monitored the unfolding transition with deuterium-exchanged staphylococcal nuclease (SNase) in D2O. These conditions circumvent all subtraction difficulties as the absorption bands of D2O and denaturant are shifted out of the amide I' region [Fabian, H., and Manstch, H. H. (1995) Biochemistry 34, 13651-13655]. A very reproducible unfolding transition is obtained for SNase. 13C-Urea-induced unfolding of SNase was found not only to be comparable to previous FTIR thermal unfolding data but also to have a denatured-state spectrum similar to those of other thermally denatured proteins. The unfolding is approximately two-state. The infrared spectra in the denatured state show evidence of some residual beta-sheet structure as well as other band components not attributable to random structure.

Circular Dichroism↗
PubMed1993

Quantitative characterization of the structure of rhodopsin in disc membrane by means of Fourier transform infrared spectroscopy.

Fourier transform infrared (FTIR) spectroscopy has been used for the detailed characterization and quantification of the secondary structure of bovine rhodopsin in native disc membranes. FTIR spectra were obtained in aqueous media, both in 1H2O and in 2H2O. Analysis of spectra by means of Fourier self-deconvolution, complemented with maximum likelihood restoration and Fourier derivative, has allowed the characterization of major amide I secondary structure-sensitive component bands of structural relevance which had not been detected before. In consequence, we show a richer secondary structure for rhodopsin than previously described. Our results indicate a total regular helix content around 51%, which would include not only the main alpha 1-type helix but also 3(10)-like helix. The presence of distorted helicoid sequences might furthermore increase to a certain extent the total helix amount. It is also indicated that a significant proportion of the amino acid residues are involved in extended/beta-structures and in reverse turns, as well as in "random" segments, which had not been directly demonstrated before. 61 +/- 4% of rhodopsin is determined to be solvent-accessible, which is a substantially higher value than previously reported. Helices account for most of the inaccessible moiety.

Animals↗
PubMed2004

Heat-induced secondary structure and conformation change of bovine serum albumin investigated by Fourier transform infrared spectroscopy.

Fourier transform infrared (FT-IR) spectra were measured for an aqueous solution (pD = 5.40) of defatted monomer bovine serum albumin (BSA) over a temperature range of 25-90 degrees C to investigate temperature-induced secondary structure and conformation changes. The curve fitting method combined with the Fourier self-deconvolution technique allowed us to explore details of the secondary structure and conformation changes in defatted BSA. Particularly striking in the FT-IR spectra was an observation of the formation of an irreversible intermolecular beta-sheet of BSA on heating above 70 degrees C. A band at 1630 cm(-1) in the spectra was assigned to short-segment chains connecting alpha-helical segments. The transition temperature for the short-segment chains connecting alpha-helical segments is lower by 17-18 degrees C, when compared to those of the alpha-helix, turn, and intermolecular beta-sheet structures of BSA, suggesting that the alpha-helix and turn structures of BSA are cooperatively denatured on heating. Moreover, the results give an important feature in heat-induced denaturation of BSA that the conformation changes occur twice around both 57 and 75 degrees C. The appearance of two peaks is interpreted by the collapse of the N-terminal BSA domain due to the crevice in the vicinity between domains I and II at low-temperature transition and by the change in cooperative unit composed of the other two BSA domains at high-temperature transition.

Animals↗
PubMedDate not supplied

[Secondary structure of tubulin on the data of Fourier transform infrared spectroscopy ].

Fourier transform infrared technique is used for identifying secondary structure of GTP/GDP tubulin in the absorbency region of its amide-I band. With this technique the band was initially resolved for 3 main and 4 satellite maxima, subsequently taken as starting values for computer resolution of the band into components of Gaussian line shape. A resolution of the spectrum into components was carried out with the FUMILI software; the resolution error was 1.5%. Improved maxima positions for the resolved components of GTP tubulin spectrum are as follows: 1682.2; 1663.7; 1653.2; 1633.4; 1625.4; 1614.0; 1605.7 cm-1, each assigned to the vibrations of a definite structural type of the protein. The main part of the structure, approximately 50%, corresponds to beta-antiparallel sheet, the contribution of alpha-coils is about of 25%. GDP tubulin shows the contribution of beta-antiparallel sheet to be greater and the contribution of alpha-coil to be less than in GTP tubulin. The difference in the maxima positions of GTP and GDP tubulin spectra does not exceed the value of +/- 3 cm-1.

Animals↗
PubMed1996

Comparative analysis of the amino- and carboxy-terminal domains of calmodulin by Fourier transform infrared spectroscopy.

Fourier transform infrared spectra were obtained for mammalian calmodulin and two of its fragments produced by limited proteolysis with trypsin TR1C (1-77) and TR2C (78-148). Experiments were done in H2O, D2O and D2O/trifluoroethanol (TFE) mixtures. Information about secondary structure was obtained from analysis of the amide I and II bands; while characteristic absorbances for tyrosine, phenylalanine and carboxylate groups were analyzed for changes in tertiary structure. Our data indicate that the secondary and tertiary structure is preserved in the two half molecules of CaM, both in the apo- and Ca(2+)-saturated state. Addition of the structure-inducing solvent TFE causes marked changes only in the apo-TR1C domain. The maximum wavenumber for the amide I band of the two domains of CaM in D2O was markedly different (1642 cm-1 for TR1C versus 1646/1648 cm-1 for Ca2+ and apo-TR2C). This renders the amide I band for the intact protein very broad in comparison to that in other proteins and is indicative of a distribution of alpha-helices with slightly different hydrogen bonding patterns.

Amino Acid Sequence↗