Signatures of hydrophobic collapse in extended proteins captured with force spectroscopy.
We unfold and extend single proteins at a high force and then linearly relax the force to probe their collapse mechanisms. We observe a large variability in the extent of their recoil. Although chain entropy makes a small contribution, we show that the observed variability results from hydrophobic interactions with randomly varying magnitude from protein to protein. This collapse mechanism is common to highly extended proteins, including nonfolding elastomeric proteins like PEVK from titin. Our observations explain the puzzling differences between the folding behavior of highly extended proteins, from those folding after chemical or thermal denaturation. Probing the collapse of highly extended proteins with force spectroscopy allows separation of the different driving forces in protein folding.
Walther
Kirstin A
KA
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Gräter
Frauke
F
Dougan
Lorna
L
Badilla
Carmen L
CL
Berne
Bruce J
BJ
Fernandez
Julio M
JM
D064211:Connectin; D019277:Entropy; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D009124:Muscle Proteins / Q000737:chemistry; D017510:Protein Folding; D011494:Protein Kinases / Q000737:chemistry
D064211:Connectin; D009124:Muscle Proteins; D011494:Protein Kinases