Fluorescence polarization studies on myosin-substrate interaction.
The degree of polarization of the intrinsic fluorescence of purified myosin was estimated. On addition of ATP, polarization of the fluorescence of myosin increased when excited at wavelengths longer than 300 nm. In kinetic studies, coupled with the decay of the increased intensity of fluorescence of myosin, the increased polarization of the fluorescence decreased when the ATP was depleted. The decay of the increased polarization of fluorescence of myosin was specific to MgATP. According to the theory of polarization of the fluorescence of proteins, it is likely that some tryptophan residues of myosin, which are responsible for the increase in the fluorescence intensity and polarization when myosin interacts with substrates, reduce their local freedom of rotation.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D005454:Fluorescence Polarization; D009132:Muscles / Q000201:enzymology; D009218:Myosins / Q000378:metabolism*; D011487:Protein Conformation; D011817:Rabbits; D013379:Substrate Specificity
D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D009218:Myosins