title: Extracting Infrared Spectra of Protein Secondary Structures Using a Library of Protein Spectra and the Ramachandran Plot.
abstract: Infrared (IR) spectra from 1200 to 1800 cm(-1) of the pure α-helix and β-sheet secondary structures have been extracted using a covariant least-squares procedure which relates a library of 40 infrared (IR) solution protein spectra from the work of Dong, Carpenter, and Caughey and amino acid fractions of the proteins based on assignments by STRIDE (secondary structure identification) of Eisenhaber and Argos. The excitonic splitting of the β-sheet structures is determined for this library of solution proteins. The method is extended to find a set of spectral basis functions that analyze IR spectra of protein samples for α-helix and β-sheet content. A rigorous error analysis including covariance, the correlations between the input library spectra, was used to justify the results and avoid less meaningful results. The utility of the results on α-helix and β-sheet regions is demonstrated by detecting protein changes due to cancer in imaging Fourier transform IR (FTIR) spectra of liver tissue slices. This work ends with a method to extract IR spectra of less prominent torsional angle distributions.
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210-1173, United States.
authors.forename: James V
authors.initials: JV
authors.lastname: Coe
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210-1173, United States.
authors.forename: Steven V
authors.initials: SV
authors.lastname: Nystrom
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210-1173, United States.
authors.forename: Zhaomin
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210-1173, United States.
authors.forename: Ran
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210-1173, United States.
authors.forename: Dominique
authors.initials: D
authors.lastname: Verreault
authors.affiliation: Department of Pathology, The Ohio State University , 4132 Graves Hall, 333 West 10th Avenue, Columbus, Ohio 43210, United States.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Hitchcock
authors.affiliation: Department of Surgery, Division of Surgical Oncology, The Ohio State University , 410 West 10th Avenue, Columbus, Ohio 43210, United States.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Martin
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University , 100 West 18th Avenue, Columbus, Ohio 43210-1173, United States.|Department of Pathology, The Ohio State University , 4132 Graves Hall, 333 West 10th Avenue, Columbus, Ohio 43210, United States.
authors.forename: Heather C
authors.initials: HC
authors.lastname: Allen
mesh_terms: D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D011506:Proteins