Rotational relaxation of 70S ribosomes by a depolarization method using triplet probes.

Abstract

Rotational relaxation on the microsecond time scale was followed by a depolarization technique using the properties of the long-lived triplet state of covalently bound labels. Two triplet probes, which efficiently bind to ribosomal proteins, are described. The rotational correlation time of 70S ribosomes of Escherichia coli was measured. The average hydrodynamic radius of the functionally active 70S particle in solution was estimated to 147 .ANG.. A comcentration dependence of the correlation time was observed, which may result from an association of the 70S ribosomes to form 100S dimers.