Abstract The SAP domain from the Saccharomyces cerevisiae Tho1 protein is comprised of just two helices and a hydrophobic core and is one of the smallest proteins whose folding has been characterised. Φ-value analysis revealed that Tho1 SAP folds through a transition state where helix 1 is the most extensively formed element of secondary structure and flickering native-like core contacts from Leu35 are also present. The contacts that contribute most to native state stability of Tho1 SAP are not formed in the transition state.
Dodson, C. A., & Arbely, E. (2015). Protein folding of the SAP domain, a naturally occurring two-helix bundle. FEBS Letters, 589(15), 1740–1747. https://doi.org/10.1016/j.febslet.2015.06.002