Direct kinetic evidence for folding via a highly compact, misfolded state.


The 2 S seed storage protein, sunflower albumin 8 (SFA-8), contains an unusually high proportion of hydrophobic residues including 16 methionines (some of which may form a surface hydrophobic patch) in a disulfide cross-linked, alpha-helical structure. Circular dichroism and fluorescence spectroscopy show that SFA-8 is highly stable to denaturation by heating or chaotropic agents, the latter resulting in a reversible two-state unfolding transition. The small m(U) (-4.7 M(-1) at 10 degrees C) and DeltaC(p) (-0.95 kcal mol(-1) K(-1)) values indicate that relatively little nonpolar surface of the protein is exposed during unfolding. Commensurate with the unusual distribution of hydrophobic residues, stopped-flow fluorescence data show that the folding pathway of SFA-8 is highly atypical, in that the initial product of the rapid collapse phase of folding is a compact nonnative state (or collection of nonnative states) that must unfold before acquiring the native conformation. The inhibited folding reaction of SFA-8, in which the misfolded state (m(M) = -0.95 M(-1) at 10 degrees C) is more compact than the transition state for folding (m(T) = -2.5 M(-1) at 10 degrees C), provides direct kinetic evidence for the transient misfolding of a protein. Study holds ProTherm entries: 6375, 6376 Extra Details: methionine; surface hydrophobic patch; alpha-helical structure;,folding pathway; transition state

Submission Details


Submitter: Connie Wang

Submission Date: April 24, 2018, 8:31 p.m.

Version: 1

Publication Details
Pandya MJ;Williams PB;Dempsey CE;Shewry PR;Clarke AR,J. Biol. Chem. (1999) Direct kinetic evidence for folding via a highly compact, misfolded state. PMID:10480890
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