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Biomedical subjects

Ulrich Bockelmann

Publications and source records attributed to Ulrich Bockelmann.

2 recordsLinked to original sources

Single-molecule manipulation of nucleic acids.

During the past decade, local force measurement techniques, such as atomic force microscopy and optical tweezers, were used to study the elastic properties and mechanically induced structural transitions of nucleic acids at the single-molecule level. Single-molecule manipulation has also increasingly been used to investigate DNA-dependent enzymatic processes, with implications for unfolding and modifying DNA, protein-DNA interactions, replication and transcription. Compared to classical techniques of molecular biology, single-molecule measurements avoid the need to average over a large number of events, and can thus potentially provide detailed and complementary information.

Biochemistry↗

Rotational drag on DNA: a single molecule experiment.

Within a single-molecule configuration, we have studied rotational drag on double stranded linear DNA by measuring the force during mechanical opening and closing of the double helix at different rates. The molecule is cranked at one end by the effect of unzipping and is free to rotate at the other end. In this configuration the rotational friction torque tau on double-stranded DNA leads to an additional contribution to the opening force. It is shown that the effect of rotational drag increases with the length of the molecule, is approximately proportional to the angular velocity of cranking, and we estimate that the torque tau is of the order of 1k(B)T for 10 000 base pairs of DNA cranked at 2000 turns per second.

Chemical Phenomena↗