Circular dichroism study on the early folding events of β-lactoglobulin entrapped in wet silica gels

Abstract

β-Lactoglobulin is a predominantly β-sheet protein that folds by forming excess α-helices within milliseconds. In this study, the refolding of β-lactoglobulin was dramatically decelerated by entrapping in wet nanoporous silica gel matrices, and monitored on a time scale of minutes or hours by far-UV circular dichroism spectroscopy. Analysis of kinetics and transient spectra allowed to define the sequence of folding events that consist of α-helical formation, β-sheet core formation, and α-to-β transition. The results suggest that the initially formed α-helices, presumably including the native α-helix, help to guide the formation of the adjacent β-sheet core.