# Stretching Single Domain Proteins: Phase Diagram and Kinetics of Force-Induced Unfolding

Source: [Stretching Single Domain Proteins: Phase Diagram and Kinetics of Force-Induced Unfolding](<https://www.sota2.com/research/paper/68fa24c02c2a3760193a8679>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T09:29:39.067Z

Authors: D. K. Klimov, D. Thirumalai

Published: 1999-05-25T20:30:26.000Z

## Abstract

Single molecule force spectroscopy reveals unfolding of domains in titin upon stretching. We provide a theoretical framework for these experiments by computing the phase diagrams for force-induced unfolding of single domain proteins using lattice models. The results show that two-state folders (at zero force) unravel cooperatively whereas stretching of non-two-state folders occurs through intermediates. The stretching rates of individual molecules show great variations reflecting the heterogeneity of force-induced unfolding pathways. The approach to the stretched state occurs in a step-wise "quantized" manner. Unfolding dynamics depends sensitively on topology. The unfolding rates increase exponentially with force f till an optimum value which is determined by the barrier to unfolding when f=0. A mapping of these results to proteins shows qualitative agreement with force-induced unfolding of Ig-like domains in titin. We show that single molecule force spectroscopy can be used to map the folding free energy landscape of proteins in the absence of denaturants.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/cond-mat/9905355>)

[PDF](<https://arxiv.org/pdf/cond-mat/9905355.pdf>)