Molecular Tumbling of Myosin S1 measured by Fluorescence Anisotropy

Petersen, Karl

University of Minnesota

Methods of Experimental Physics Spring 2012

Abstract

Myosin S1 is the catalytic domain of the myosin molecular motor. The rate of tumbling in solution can be determined from the anisotropy function which decays at the time scale of the motion. To find the anisotropy function we will measure vertical and horizontal emission of AEDANS-labeled myosin S1 using a time-resolved spectrometer. We found that our sample contained free and immobile fractions of S1 (~45% immobile). Using nonlinear regression we found the rotational correlation time of free S1 was (75±11) ns, a departure from the previously reported value of (220±5) ns.