The Folding of Spectrin Domains I: Wild-type Domains Have the Same Stability but very Different Kinetic Properties

• Published in: Journal of molecular biology Vol. 344; no. 1; pp. 195 - 205
• Main Authors: Scott, Kathryn A., Batey, Sarah, Hooton, Karen A., Clarke, Jane
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 12.11.2004
• Subjects: Animals; Brain Chemistry; Chickens; Drug Stability; helix-bundle; homologue; Kinetics; Models, Molecular; Protein Folding; Protein Structure, Tertiary; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; residual structure; spectrin; Spectrin - chemistry; Spectrin - genetics; Thermodynamics; CD; protein folding; spectrin; residual structure; homologue; helix-bundle
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2004.09.037

The study of proteins with the same architecture, but different sequence has proven to be a valuable tool in the protein folding field. As a prelude to studies on the folding mechanism of spectrin domains we present the kinetic characterisation of the wild-type forms of the 15th, 16th, and 17th domains of chicken brain α-spectrin (referred to as R15, R16 and R17, respectively). We show that the proteins all behave in a two-state manner, with different kinetic properties. The folding rate varies remarkably between different members, with a 5000-fold variation in folding rate and 3000-fold variation in unfolding rate seen for proteins differing only 1 kcal mol −1 in stability. We show clear evidence for significant complexity in the energy landscape of R16, which shows a change in amplitude outside the stopped-flow timescale and curvature in the unfolding arm of the chevron plot. The accompanying paper describes the characterisation of the folding pathway of this domain.