Equilibrium titrations of acid-induced unfolding–refolding and salt-induced molten globule of cytochrome c by FT-IR spectroscopy

Secondary Structures Associated With Alkaline Transition of Horse Heart Ferricytochrome C: An FTIR Study

“…There was a significant decrease of non-repetitive secondary structure between the results at neutral pH (7.0) and in the neigbourhood of alkaline transition at pH 9.5. Although it was in agreement the work reported result by Dong and Lam (2005), that unfolding of cytochrome c due to α-helix structure was as a result of acid effect. The β-turns content was higher at neutral pH (15.80%) as against (30.60%) in the neigbourhood of alkaline transition of ferricytochrome c at pH 9.5.…”

“…Acid-induced unfolding of cytochrome c occurs in a single cooperative transition accompanied by the loss of axial Met-80-heme ligation under low ionic strength conditions (Tonge et al, 1989). Simple treatment of cytochrome c by potassium ferricyanide for the purpose of fully oxidizing it could prevent achieving the maximum unfolded state, due to strong interaction between the ferricyanide ions and cytochrome c (Dong and Lam, 2005). The cytochrome c in this work reveals a much regular secondary structural elements.…”

“…Unlike other secondary structures the β-turns structures are closely associated with the tertiary structure of proteins (Dong et al, 1995;Dong et al, 2002). Conformational changes in the tertiary structural level are undoubtedly accompanied by structural changes at β-turns, which in turn will be reflected in the spectral changes at the region assignable to the β-turns (Dong and Lam, 2005). Significant amount of β-turns at neutral pH (7.0) was lower than the value obtained in the neigbourhood of alkaline transition at pH 9.5.…”

Unexpected improvement in stability and utility of cytochrome c by solution in biocompatible ionic liquids

“…The spectra show loss of turn structure (multiple bands between 1,688 and 1,666/cm) and increase of b sheet structures (multiple bands between 1,642 and 1,624/cm). These secondary structure changes are strongly suggestive of protein unfolding and aggregation in the aqueous sample (Dong and Lam, 2005). Lau et al (2004) have utilized similar FTIR methods to investigate structural changes in candida antarctica lipase B in ionic liquid; in the ionic liquids used in that work, structure changes were observed, in contrast to the present work.…”

Self‐Organizing Large‐Scale Extracellular‐Matrix Protein Networks

“…IR Spectral Analysis : Deconvolution and curve fitting were used to decompose the amide І band into its constituents for the peak assignment in order to analyze the secondary structures . Deconvolution was performed by using Resolution Pro FTIR software (Agilent Technologies) with a fixed half‐width ( W = 15 cm −1 ) and a fixed enhancement factor ( K = 2.4) .…”