Infrared Spectra of Globular Proteins in Aqueous Solution

Koenig, Jack L.; Tabb, D. L.

doi:10.1007/978-94-009-9070-8_15

Cited by 33 publications

(10 citation statements)

References 20 publications

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“…The band near 1656 cm-' can be unambiguously assigned to a-helical structures, the assignment being consistent with both theoretical calculations (Krimm and Bandekar, 1986) and with the observation of bands at this wavenumber in the spectra of a-helical polypeptides and proteins Susi, 1969;Susi and Byler, 1986;Koenig and Tabb, 1980). The atypical band observed at 1648 cm-' appeared at values too high to be assigned to random structures.…”

Section: Resolution-enhanced Spectra Recorded In Do Buffersupporting

confidence: 86%

“…Structural studies are usually based on evaluations of the amide-1-band contour, located approximately at 1600-1700 cm-'. A number of polypeptides and proteins have been examined and the various component bands of amide I were related to specific conformations (a-helix, P-sheet, turn; Krimm, 1962;Susi et al, 1967;Susi, 1969;Koenig and Tabb, 1980). Using comparative analysis and theoretical studies (Krimm, 1962;Miyazawa and Blout, 1961;Kennedy et al, 1991;Wilder et al, 1992;Arrondo et al, 1988) good agreement was obtained with other methods of secondary-structure investigation.…”

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confidence: 90%

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Secondary structure and temperature behaviour of acetylcholinesterase

Görne-Tschelnokow

Naumann

Weise

et al. 1993

European Journal of Biochemistry

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The secondary structure of the acetylcholinesterase and its temperature behaviour have been investigated using Fourier-transform infrared (FTIR) spectroscopy. The data are compared to the structure obtained by X-ray analysis of the crystalline enzyme. The secondary structure was determined using the spectral features observed in the amide-I band (H,O buffer) and amide-I' band (D,O buffer) at 1600-1700 cm-I, taking advantage of resolution-enhancement techniques along with least-squares band-fitting procedures. The relative amounts of different secondary-structure elements, 34-36% for a-helices, 19-25% for p-sheets, 15-16% for turns and 13-17% for irregular structures, were estimated. These data, obtained with the enzyme in solution, correlate well with X-ray data of the crystalline protein [Sussman, J. L., Hard, M., Frolow, F., Oefner, C., Goldman, A., Toker, L. The relationship between the thermally induced loss of enzyme activity and secondary-structure changes has also been investigated. The decrease in enzyme activity to zero at 30-40 "C was accompanied only by minor changes in the secondary structure. At 55-6OoC, denaturation of AChE occurs. In this temperature range, all bands assigned to the various secondary-structure elements abruptly disappear in a co-operative and irreversible manner, whereas the &aggregation bands (at 1622 cm-' and the corresponding high-frequency band) increase in intensity at the same rate.Acetylcholinesterase (AChE) is a key molecule involved in nerve-impulse transmission at cholinergic synapses. It rapidly hydrolyses the neurotransmitter acetylcholine and thus terminates the signal. As the main point of attack of most insecticides and chemical-warfare agents (nerve gases), AChE is of considerable interest. Moreover, structural research on AChFi is relevant because AChE is the best characterized member of the protein family of serine esterases, as defined on the basis of sequence homology (Myers et al., 1988;Krejci et al., 1991;Ollis et al., 1992). Since disulfide bridges are highly conserved within this protein family, it is plausible that AChE shares secondary-structure and tertiarystructure motifs with these related proteins.The three-dimensional structure of crystallized AChEi has been recently reported (Sussman et al., 1991). The AChE monomer is an ellipsoidally shaped alp-protein, with dimensions of 4.3 nm X 6.0 nm X 6.5 nm, which contains a 12-stranded mixed P-sheet surrounded by 14 a-helices. From the X-ray data, it can be concluded that the a-structure content is approximately 32% and that the p-structure content is 15 %. Even with detailed structural information from X-ray crystallography, spectroscopic methods for investigating secondary structure have not lost their attraction. Firstly, spectroscopic methods allow the direct measurement of proteins in solution (in a more native state) and they have considerable potential for exploring conformational changes, such as temperature-dependent processes, which might not, in principle, be amenable to X-ray analysis. Secondly, ...

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Section: Resolution-enhanced Spectra Recorded In Do Buffersupporting

confidence: 86%

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confidence: 90%

Secondary structure and temperature behaviour of acetylcholinesterase

Görne-Tschelnokow

Naumann

Weise

et al. 1993

European Journal of Biochemistry

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“…Another mode of the amide group, the CO stretch (amide I) is absent in this region, indicating a parallel alignment of the CO bond with respect to the surface plane. Moreover, the position of the amide II mode at 1562 cm -1 indicates that the amide groups are laterally hydrogen-bonded in SAM 3 . ,,, During the temperature ramp, the amide II peak gradually shifts toward lower frequencies, a behavior that is interpreted as a lowering of the degree of hydrogen bonding. , From Figure b, it can be seen that the red shift accelerates at around 400 K and stabilizes near 1545 cm -1 at 442 K. The intensity of the amide II decreases sharply during the next step. Note also that the drop of the amide II intensity is paralleled with the appearance of the amide I mode as a broad feature at around 1670 cm -1 .…”

Section: Resultsmentioning

confidence: 95%

Thermal Stability of Self-Assembled Monolayers: Influence of Lateral Hydrogen Bonding

et al. 2002

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Temperature-programmed desorption (TPD) of self-assembled monolayers (SAMs) on gold is investigated by using in parallel mass spectrometry (MS) and infrared reflection−absorption spectroscopy (IRAS). Monolayers formed by HS(CH2) n −OH (n = 18, 22) and HS(CH2)15−CONH−(CH2CH2O)−H (EG1) are compared to reveal the influence of specifically introduced hydrogen-bonding groups on their thermal stability. The overall desorption process of the above molecules is found to occur in two main steps; a disordering of the alkyl chains followed by a complex series of decomposition/desorption reactions. The final step of the process involves desorption of sulfur from different chemisorption states. The amide-group-containing SAM, which is stabilized by lateral hydrogen bonds, displays a substantial delay of the alkyl chain disordering by about 50 K, as compared to the linear chain alcohols HS(CH2) n −OH. Moreover, the decomposition of the alkyls and the onset of sulfur desorption occur at a temperature that is higher by approximately 25 K as compared to the HS(CH2)18−OH SAM. The desorption process is also studied for two oligo(ethylene glycol)-terminated SAMs, HS(CH2)15−X−(CH2CH2O)4−H (EG4-SAMs), where X is −CONH− and −COO− linking groups. In addition to the molecular chain disordering, the decomposition/desorption process of the EG4-SAMs occurs in two steps. The first is associated with the loss of the oligomer portion and the second with the desorption of the alkylthiolate part of the molecule. Our study points out that lateral hydrogen bonding, introduced via amide groups, is a convenient way to improve the thermal stability of alkanthiolate SAMs.

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“…In various protein secondary structures, the CO of one amino acid couples differently with other amino acids, which introduces shifts of the amide I and amide II bands. Therefore, these IR absorptions, especially the amide I band, have been useful indicators for the determination of the secondary structure of proteins. − However, there are few if any reports of FTIR measurement of a protein monolayer immobilized on a substrate surface, mainly due to the low sensitivity of conventional dispersive IR instruments and the difficulties encountered in achieving the accurate subtraction of the strong water absorption found in the amide I region. , By using a high-sensitivity FTIR instrument, we report here the IR absorption of Mb chemisorbed to a siloxane surface.…”

Section: Resultsmentioning

confidence: 99%

Surface-Linked Molecular Monolayers of an Engineered Myoglobin: Structure, Stability, and Function

et al. 1996

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The maintenance of active conformation and biological function is important for the development of solid substrate immobilized biomacromolecules for material applications. A protein monolayer was obtained on SiO2 substrates by chemically linking a site-directed mutant of sperm whale myoglobin, A126C, which has a unique and reactive cysteine residue on its surface, to a thiol specific functional group on the silane-derivatized substrates. Fourier transform infrared (FTIR) spectroscopy of this protein monolayer suggests that a native-like secondary structure is retained for the immobilized myoglobin. In addition, the immobolized myoglobin retains its ability to bind carbon monoxide. Structural changes in the surface-bound protein were examined under variation of temperature, pH, urea concentration, and ethanol content by UV−vis absorption spectroscopy. The densely packed protein, roughly 60% surface coverage of the substrate, is as resilient to high temperature, low-pH environment, and high concentration of urea as myoglobin solution is at low concentration. Surprisingly, we found that after immobilization, the protein resists ethanol denaturation more efficiently than a diluted solution of 1 μM myoglobin with ethanol as the cosolvent. Intriguingly, the secondary structure of the immobilized myoglobin was preserved after 30 min incubation at 150 °C, as determined by FTIR at room temperature.

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Infrared Spectra of Globular Proteins in Aqueous Solution

Cited by 33 publications

References 20 publications

Secondary structure and temperature behaviour of acetylcholinesterase

Secondary structure and temperature behaviour of acetylcholinesterase

Thermal Stability of Self-Assembled Monolayers: Influence of Lateral Hydrogen Bonding

Surface-Linked Molecular Monolayers of an Engineered Myoglobin: Structure, Stability, and Function

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