Analysis of the molten globule state of bovine α-lactalbumin by using vibrational circular dichroism

초록

We investigated molten globule state of alpha-lactalbumin by using vibrational circular dichroism (VCD) and two-dimensional (2D) correlation spectroscopy. To investigate details on the denaturation mechanism of alpha-lactalbumin, 2D correlation spectroscopy was applied to the pH-dependent VCD spectra of alpha-lactalbumin aqueous solutions. The denaturation transition point of alpha-lactalbumin was determined by 2D gradient mapping method. Large spectral changes of VCD spectra were observed at pH 4.75 and 2.75 in 2D gradient map, which are transition points. Based on analysis of 2D VCD correlation spectra, we can suggest the sequence change from pre-molten globule state to molten globule state. Intermolecular beta-sheet changed first, and then lower-frequency beta-sheet structure changed before alpha-helices with continued lowering of the pH. (C) 2012 Elsevier B.V. All rights reserved.

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