title: Probing conformational changes of proteins by quantitative second-derivative infrared spectroscopy.
abstract: Probing protein conformational changes plays a crucial role in protein structure and function studies. However, the lack of efficient biophysical techniques makes it difficult to obtain the distinct behaviors of different secondary structure elements in a protein upon perturbation. This paper presents a discussion of the two major problems, the effect of sidelobes and different half-width at half-height (HWHH) values, encountered in quantitative second-derivative infrared (QSD-IR) spectroscopy and introduces the development of two criteria for checking the validity of the results obtained using the QSD-IR method. It was found that neither the sidelobes nor the HWHH significantly affected the quantitative result of protein conformational changes by using poly-l-lysine and hemoglobin as model proteins. A case study of bovine serum albumin (BSA) thermal aggregation suggested that the thermal transition of BSA was a process involving sequential events, and the two helical components were found to have a distinct response to heat perturbation. These results were confirmed by two-dimensional infrared correlation spectroscopy and by results in literature, suggesting that the QSD-IR method might be a potentially powerful tool to probe the distinct response of different secondary structures to perturbation.
authors.affiliation: Department of Biological Sciences and Biotechnology and State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Yong-Bin
authors.initials: YB
authors.lastname: Yan
mesh_terms: D000818:Animals; D002417:Cattle; D011487:Protein Conformation; D011489:Protein Denaturation; D015203:Reproducibility of Results; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013055:Spectrophotometry, Infrared / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D012710:Serum Albumin, Bovine