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States and transitions during forced unfolding of a single spectrin repeat
Author(s) -
Lenne P.-F,
Raae A.J,
Altmann S.M,
Saraste M,
Hörber J.K.H
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01704-x
Subject(s) - spectrin , antiparallel (mathematics) , force spectroscopy , cytoskeleton , actin , epb41 , chemistry , biophysics , coiled coil , crystallography , protein structure , molecule , biology , physics , biochemistry , cell , organic chemistry , quantum mechanics , magnetic field
Spectrin is a vital and abundant protein of the cytoskeleton. It has an elongated structure that is made by a chain of so‐called spectrin repeats. Each repeat contains three antiparallel α‐helices that form a coiled‐coil structure. Spectrin forms an oligomeric structure that is able to cross‐link actin filaments. In red cells, the spectrin/actin meshwork underlying cell membrane is thought to be responsible for special elastic properties of the cell. In order to determine mechanical unfolding properties of the spectrin repeat, we have used single molecule force spectroscopy to study the states of unfolding of an engineered polymeric protein consisting of identical spectrin domains. We demonstrate that the unfolding of spectrin domains can occur in a stepwise fashion during stretching. The force–extension patterns exhibit features that are compatible with the existence of at least one intermediate between the folded and the completely unfolded conformation. Only those polypeptides that still contain multiple intact repeats display intermediates, indicating a stabilisation effect. Precise force spectroscopy measurements on single molecules using engineered protein constructs reveal states and transitions during the mechanical unfolding of spectrin. Single molecule force spectroscopy appears to open a new window for the analysis of transition probabilities between different conformational states.