Winslow S. Caughey

Bio: Winslow S. Caughey is an academic researcher from Arizona State University. The author has contributed to research in topics: Infrared spectroscopy & Deuteroporphyrins. The author has an hindex of 23, co-authored 31 publications receiving 3187 citations. Previous affiliations of Winslow S. Caughey include Colorado State University.

Protein secondary structures in water from second-derivative amide I infrared spectra.

Abstract: Infrared spectra have been obtained for 12 globular proteins in aqueous solution at 20 degrees C. The proteins studied, which vary widely in the relative amounts of different secondary structures present, include myoglobin, hemoglobin, immunoglobulin G, concanavalin A, lysozyme, cytochrome c, alpha-chymotrypsin, trypsin, ribonuclease A, alcohol dehydrogenase, beta 2-microglobulin, and human class I major histocompatibility complex antigen A2. Criteria for evaluating how successfully the spectra due to liquid and gaseous water are subtracted from the observed spectrum in the amide I region were developed. Comparisons of second-derivative amide I spectra with available crystal structure data provide both qualitative and quantitative support for assignments of infrared bands to secondary structures. Band frequency assignments assigned to alpha-helix, beta-sheet, unordered, and turn structures are highly consistent among all proteins and agree closely with predictions from theory. alpha-Helix and unordered structures can each be assigned to only one band whereas multiple bands are associated with beta-sheets and turns. These findings demonstrate a method of analysis of second-derivative amide I spectra whereby the frequencies of bands due to different secondary structures can be obtained. Furthermore, the band intensities obtained provide a useful method for estimating the relative amounts of different structures.

An infrared study of nitric oxide bonding to heme B and hemoglobin A. Evidence for inositol hexaphosphate induced cleavage of proximal histidine to iron bonds

Abstract: Five- and six-coordinate nitrosyl hemes have been prepared and their infrared, electron paramagnetic resonance (EPR), and visible-Soret spectra compared with the corresponding spectra for nitrosyl hemoglobin A (Hba-NO) determined both in the presence and the absence of inositol hexaphosphate (IHP). The five- and six-coordinate NO complexes prepared from either dipyridine or pyridine carbonyl protoheme dimethyl ester had N-O stretch bands (nuno) near 1675 and 1625 cm-1, respectively. These frequencies are sensitive to change in solvent (nuno decreased as the dipole moment of the solvent increased) and, with six-coordinate species, to changes in trans ligand. However, these solvent and trans ligand effects were small compared with the difference (ca. 50 cm-11) between five- and six -coordinate species. The nature of the trans ligand affected the relative proportions of the two...

Infrared methods for study of hemoglobin reactions and structures.

Abstract: Publisher Summary This chapter presents the experimental approaches and interpretations of data for ligand spectra, microspectroscopy, thiol spectra, and amide I spectra. Methods using infrared (IR) spectroscopy provide important, often unique, means for the study of the reactions and structures of hemoglobins (Hb). The amide I bands, primarily because of the carbonyl groups in the peptide bonds that constitute the linkages between the amino acid residues of the Hb molecule, can be utilized for the qualitative and quantitative determination of α-helix, random, β-sheet, and turn secondary structures. Thus, the accurate measurement of an IR band at a given wavelength depends on the absorption of the medium as well as on protein concentration, intrinsic band intensity, and the distance through the sample traversed by the IR radiation. Improvements in IR instrumentation and in data analysis have greatly enhanced the sensitivity of the IR method applied to aqueous solutions.

Redox-dependent changes in .beta.-extended chain and turn structures of cytochrome c in water solution determined by second derivative amide I infrared spectra

Abstract: The redox-dependent changes in secondary structure of cytochromes c from horse, cow, and dog hearts in water at 20 OC have been determined by amide I infrared spectroscopy. Second derivative amide I spectra were obtained by use of a procedure that includes a convenient method for the effective subtraction of the spectrum of water vapor in the system. The band at 1657 cm-' representing the helix structure was unaffected by a change in redox state whereas changes in bands due to turns at 1680, 1672, and 1666 cm-', unordered structure at 1650 cm-', and @-structures at 1632 and 1627 cm-' occurred. About one-fourth of the @-extended chain spectral region and one-fifth of the @-turn region (involving a total of approximately 9-13 residues) were sensitive to the oxidation state of heme iron. No significant changes in the secondary structure of either the reduced or oxidized protein due to changes in ionic strength were detected. The localized structural rearrangements triggered by the changes in oxidation state of heme iron are consistent with differences in the binding of heme iron to a histidine imidazole nitrogen and a methionine sulfur atom from the ,&extended chain. The demonstrated ability to obtain highly reproducible second derivative amide I infrared spectra confirms the unique utility of such spectral measurements for localization of subtle changes in secondary structure within a protein, especially for changes among the multiple turns and 6-structures.

Fourier Transform Infrared Spectroscopic Analysis of Protein Secondary Structures

Abstract: Infrared spectroscopy is one of the oldest and well established experimental techniques for the analysis of secondary structure of polypeptides and proteins. It is convenient, non-destructive, requires less sample preparation, and can be used under a wide variety of conditions. This review introduces the recent developments in Fourier transform infrared (FTIR) spectroscopy technique and its applications to protein structural studies. The experimental skills, data analysis, and correlations between the FTIR spectroscopic bands and protein secondary structure components are discussed. The applications of FTIR to the secondary structure analysis, conformational changes, structural dynamics and stability studies of proteins are also discussed.

Heme oxygenase-1/carbon monoxide: from basic science to therapeutic applications.

Abstract: The heme oxygenases, which consist of constitutive and inducible isozymes (HO-1, HO-2), catalyze the rate-limiting step in the metabolic conversion of heme to the bile pigments (i.e., biliverdin and bilirubin) and thus constitute a major intracellular source of iron and carbon monoxide (CO). In recent years, endogenously produced CO has been shown to possess intriguing signaling properties affecting numerous critical cellular functions including but not limited to inflammation, cellular proliferation, and apoptotic cell death. The era of gaseous molecules in biomedical research and human diseases initiated with the discovery that the endothelial cell-derived relaxing factor was identical to the gaseous molecule nitric oxide (NO). The discovery that endogenously produced gaseous molecules such as NO and now CO can impart potent physiological and biological effector functions truly represented a paradigm shift and unraveled new avenues of intense investigations. This review covers the molecular and biochemical characterization of HOs, with a discussion on the mechanisms of signal transduction and gene regulation that mediate the induction of HO-1 by environmental stress. Furthermore, the current understanding of the functional significance of HO shall be discussed from the perspective of each of the metabolic by-products, with a special emphasis on CO. Finally, this presentation aspires to lay a foundation for potential future clinical applications of these systems.

The Use and Misuse of FTIR Spectroscopy in the Determination of Protein Structure

Abstract: Fourier transform infrartd (FTIR) spectroscopy is an established tool for the structural character- ization of proteins. However, many potential pitfalls exist for the unwary investigator. In this review we critically assess the application of FIlR spectroscopy to the determination of protein structure by (1) outlining the principles underlying protein secondary structure determination by FZZR spectroscopy. (2) highhghting the situations in which FZZR spectroscopy should be considered the technique of choice, (3) discussing the manner in which experiments should be conducted to derive as much physiologically relevant information as possible, and (4) outlining current methods for the determination of secondary structure from infrared spectm of proteins,