Probing structural heterogeneities and fluctuations of nucleic acids and denatured proteins.

ABSTRACT: We study protein and nucleic acid structure and dynamics using single-molecule FRET and alternating-laser excitation. Freely diffusing molecules are sorted into subpopulations based on single-molecule signals detected within 100 micros to 1 ms. Distance distributions caused by fluctuations faster than 100 micros are studied within these subpopulations by using time-correlated single-photon counting. Measured distance distributions for dsDNA can be accounted for by considering fluorophore linkers and fluorophore rotational diffusion, except that we find smaller fluctuations for internally labeled dsDNA than DNA with one of the fluorophores positioned at a terminal site. We find that the electrostatic portion of the persistence length of short single-stranded poly(dT) varies approximately as

SUBMITTER: Laurence TA 

PROVIDER: S-EPMC1297681 | biostudies-literature | 2005 Nov

REPOSITORIES: biostudies-literature