title: Effect of thermal denaturation, inhibition, and cleavage of disulfide bonds on the low-frequency Raman and FTIR spectra of chymotrypsin and albumin.
abstract: The analysis of the structure-function relationship is extremely important in the study of proteins. The importance of function-related motions of large parts or subglobules of protein molecules stimulates the spectroscopic study in the low-frequency (terahertz) domain. However, only tentative assignments are available and the spectroscopic data are insufficiently discussed in terms of structural changes. This work is aimed at the analysis of regularities of changes in the low-frequency (100 to 600 cm(-1)) FTIR and Raman spectra of proteins related to their structural modifications. We study the spectra of two proteins with substantially different structures (albumin and chymotrypsin) and the spectra of samples in which the structures of protein molecules are modified using inhibition, thermal denaturation, and cleavage of disulfide bonds. The results indicate that the low-frequency spectral interval can be used to characterize protein conformations. Correlated variations in the intensities of several low-frequency bands are revealed in the spectra of the modified proteins. The strongest spectral changes are caused by thermal denaturation of proteins, and the effect of cleavage of disulfide bonds is generally weaker. It is demonstrated that the inhibitor binding in the active site causes spectral changes that can be compared to the changes induced by thermal denaturation.
authors.affiliation: Lomonosov Moscow State University, Faculty of Physics, Leninskie gory 1, Moscow, Russia 119991.
authors.forename: Nikolay N
authors.initials: NN
authors.lastname: Brandt
authors.affiliation: International Laser Center, Leninskie gory 1/62, Moscow, Russia 119991.
authors.forename: Andrey Yu
authors.initials: AY
authors.lastname: Chikishev
authors.affiliation: Lomonosov Moscow State University, Faculty of Physics, Leninskie gory 1, Moscow, Russia 119991.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Mankova
authors.affiliation: Lomonosov Moscow State University, Faculty of Chemistry, Leninskie gory 1, Moscow, Russia 119991.
authors.forename: Inna K
authors.initials: IK
authors.lastname: Sakodynskaya
mesh_terms: D000418:Albumins / Q000737:chemistry*; D000818:Animals; D020134:Catalytic Domain; D002417:Cattle; D002918:Chymotrypsin / Q000737:chemistry*; D004220:Disulfides; D004229:Dithiothreitol / Q000737:chemistry; D006358:Hot Temperature; D008024:Ligands; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D000418:Albumins; D004220:Disulfides; D008024:Ligands; D011506:Proteins; D002918:Chymotrypsin; D004229:Dithiothreitol