A statistical mechanical description of flexible and semiflexible polymer chains in a poor solvent is developed in the constant force and constant distance ensembles. We predict the existence of many intermediate states at low temperatures stabilized by the force. A unified response to pulling and compressing forces has been obtained in the constant distance ensemble. We show the signature of a...

Stress-specific activation of the chaperone Hsp33 requires the unfolding of a central linker region. This activation mechanism suggests an intriguing functional relationship between the chaperone's own partial unfolding and its ability to bind other partially folded client proteins. However, identifying where Hsp33 binds its clients has remained a major gap in our understanding of Hsp33's worki...

Pathways of unfolding a protein depend in principle on the perturbation-whether it is temperature, denaturant, or even forced extension. Widely-shared, helical-bundle spectrin repeats are known to melt at temperatures as low as 40-45 degrees C and are also known to unfold via multiple pathways as single molecules in atomic force microscopy. Given the varied roles of spectrin family proteins in ...

Little is known about the role of protein dynamics in directing protein unfolding along a specific pathway and about the role played by chemical denaturants in modulating the dynamics and the initiation of unfolding. In this study, deuterium-hydrogen exchange (HX) detected by electrospray ionization mass spectrometry (ESI-MS) was used to study the unfolding of the SH3 domain of the PI3 kinase. ...

We show that every orthogonal polyhedron of genus g ≤ 2 can be unfolded without overlap while using only a linear number of orthogonal cuts (parallel to the polyhedron edges). This is the first result on unfolding general orthogonal polyhedra beyond genus-0. Our unfolding algorithm relies on the existence of at most 2 special leaves in what we call the “unfolding tree” (which ties back to the g...

Unfolding intermediates have been found only rarely in earlier studies, and how a protein unfolds is therefore poorly understood. In this paper, we show experimental evidence for multiple pathways and multiple intermediates during unfolding reaction of O(6)-methylguanine-DNA methyltransferase from hyperthermophile Thermococcus kodakaraensis (Tk-MGMT). The unfolding profiles monitored by far-UV ...