title: Two-dimensional infrared correlation spectroscopy study of sequential events in the heat-induced unfolding and aggregation process of myoglobin.
abstract: Unfolding and aggregation are basic problems in protein science with serious biotechnological and medical implications. Probing the sequential events occurring during the unfolding and aggregation process and the relationship between unfolding and aggregation is of particular interest. In this study, two-dimensional infrared (2D IR) correlation spectroscopy was used to study the sequential events and starting temperature dependence of Myoglobin (Mb) thermal transitions. Though a two-state model could be obtained from traditional 1D IR spectra, subtle noncooperative conformational changes were observed at low temperatures. Formation of aggregation was observed at a temperature (50-58 degrees C) that protein was dominated by native structures and accompanied with unfolding of native helical structures when a traditional thermal denaturation condition was used. The time course NMR study of Mb incubated at 55 degrees C for 45 h confirmed that an irreversible aggregation process existed. Aggregation was also observed before fully unfolding of the Mb native structure when a relative high starting temperature was used. These findings demonstrated that 2D IR correlation spectroscopy is a powerful tool to study protein aggregation and the protein aggregation process observed depends on the different environmental conditions used.
authors.affiliation: NMR Laboratory, Department of Biological Sciences and Biotechnology, and State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China. ybyan@mail.tsinghua.edu.cn
authors.forename: Yong-Bin
authors.initials: YB
authors.lastname: Yan
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Hua-Wei
authors.initials: HW
authors.lastname: He
authors.forename: Xin-Yao
authors.initials: XY
authors.lastname: Hu
authors.forename: Ri-Qing
authors.initials: RQ
authors.lastname: Zhang
authors.forename: Hai-Meng
authors.initials: HM
authors.lastname: Zhou
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D006736:Horses; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D009206:Myocardium / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry*; D011489:Protein Denaturation; D017510:Protein Folding; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013696:Temperature; D013997:Time Factors
chemical_list: D009211:Myoglobin