Alcohol-induced structural transitions in the acid-denatured Bacillus licheniformis α-amylase

• Main Authors: Halim, A.A.A., Zaroog, M.S., Kadir, H.A., Tayyab, S.
• Format: Article
• Published: Elsevier 2017
• Subjects: Q Science (General); QD Chemistry; QH Natural history
• Online Access: http://eprints.um.edu.my/19178/; http://dx.doi.org/10.1016/j.jscs.2014.04.002
• Institution: Universiti Malaya

Alcohol-induced structural changes in the acid-denatured Bacillus licheniformis α-amylase (BLA) at pH 2.0 were studied by far-ultra violet circular dichroism, intrinsic, three-dimensional and 8-anilino-1-naphthalene sulfonic acid (ANS) fluorescence, acrylamide quenching and thermal denaturation. All the alcohols used in this study produced partial refolding in the acid-denatured BLA as evident from the increased mean residue ellipticity at 222 nm, increased intrinsic fluorescence and decreased ANS fluorescence. The order of effectiveness of these alcohols to induce a partially folded state of BLA was found to be: 2,2,2-trifluoroethanol/tert-butanol > 1-propanol/2-propanol > 2-chloroethanol > ethanol > methanol. Three-dimensional fluorescence and acrylamide quenching results obtained in the presence of 5.5 M tert-butanol also suggested formation of a partially folded state in the acid-denatured BLA. However, 5.5 M tert-butanol-induced state of BLA showed a non-cooperative thermal transition. All these results suggested formation of a partially folded state of the acid-denatured BLA in the presence of these alcohols. Furthermore, their effectiveness was found to be guided by their chain length, position of methyl groups and presence of the substituents.