The denatured state under native conditions: a non-native-like collapsed state of N-PGK.

摘要: The guanidinium-denatured state of the N-domain phosphoglycerate kinase (PGK) has been characterized using solution NMR. Rather than behaving as a homogenous ensemble random coils, chemical shift changes for majority backbone amide resonances indicate that denatured undergoes two definable equilibrium transitions upon titration with guanidinium, in addition to major refolding event. (13)C and (15)N both intermediary states have distinct helical character. At denaturant concentrations immediately above mid-point unfolding, size-exclusion chromatography shows N-PGK compact, form, suggesting it forms molten globule. Within this globule, helices extend into some regions become beta strands native state. This predisposition extensive non-native-like conformation, illustrates that, rather directing folding, conformational pre-organization can compete normal folding direction. corresponding reduction control direction proteins larger, could thus constitute restriction on size protein domains.