In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 98, No. 25 ( 2001-12-04), p. 14362-14367
Abstract:
The global configuration of individual, surface-adsorbed molecules
of the giant muscle protein titin, labeled with rhodamine conjugates, was followed with confocal microscopy. Fluorescence-emission
intensity was reduced because of self-quenching caused by the close spacing between rhodamine dye molecules that formed dimers. In the
presence of chemical denaturants, fluorescence intensity increased, reversibly, up to 5-fold in a fast reaction; the kinetics were followed
at the single-molecule level. We show that dimers formed in a concentrated rhodamine solution dissociate when exposed to chemical
denaturants. Furthermore, titin denaturation, followed by means of tryptophan fluorescence, is dominated by a slow reaction.
Therefore, the rapid fluorescence change of the single molecules reflects the direct action of the denaturants on rhodamine dimers
rather than the unfolding/refolding of the protein. Upon acidic denaturation, which we have shown not to dissociate rhodamine dimers,
fluorescence intensity change was minimal, suggesting that dimers persist because the unfolded molecule has contracted into a small
volume. The highly contractile nature of the acid-unfolded protein molecule derives from a significant increase in chain flexibility. We
discuss the potential implications this finding could have for the passive mechanical behavior of striated muscle.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.191494098
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2001
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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