@article{11792, keywords = {folding dynamics, membrane proteins, retinal}, author = {Hao Yu and Patrick Heenan and Devin Edwards and Lyle Uyetake and Thomas Perkins}, title = {Quantifying the initial unfolding of bacteriorhodopsin reveals retinal stabilization}, abstract = {The forces that stabilize membrane proteins remain elusive to precise quantification. Particularly important, but poorly resolved, are the forces present during the initial unfolding of a membrane protein, where the most native set of interactions is present. A high-precision, atomic force microscopy assay was developed to study the initial unfolding of bacteriorhodopsin. A rapid near-equilibrium folding between the first three unfolding states was discovered, the two transitions corresponded to the unfolding of five and three amino acids, respectively, when using a cantilever optimized for 2 μs resolution. The third of these states was retinal-stabilized and previously undetected, despite being the most mechanically stable state in the whole unfolding pathway, supporting 150 pN for more than 1 min. This ability to measure the dynamics of the initial unfolding of bacteriorhodopsin provides a platform for quantifying the energetics of membrane proteins under native-like conditions.}, year = {2019}, journal = {Angewandte Chemie}, volume = {131}, pages = {1724-1727}, month = {2019-01}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/ange.201812072}, doi = {10.1002/ange.v131.610.1002/ange.201812072}, }