pH-induced structural changes of ovalbumin studied by 2D correlation IR spectroscopy

초록

The secondary structural changes of pH-induced ovalbumin during the transition from native state into intermediate state were studied with the use of 2D correlation spectroscopy and principal component analysis. 2D correlation spectra constructed from the pH-dependent IR spectra of ovalbumin solution revealed the following scenario of the intensity changes with pH decrease. When pH decreased from 5.5 and 3.6 intensity of components attributed to the beta-turns, the alpha-helical elements, and native beta-sheets increased. It was caused by protonation induced changes in environment of these elements. When the protonation of the acidic groups were finalized the system adopted the intermediate structure. It was accompanied by weak structural changes that mainly included the beta-turns and the a-helices. In extreme acidic conditions at pH below pH 2 the intermediate structure was no longer stable and oligomers rich in the beta-sheet structure were formed. (C) 2014 Elsevier B.V. All rights reserved.

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