Hegyi G, Szilágyi L, Belágyi J
Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary.
Eur J Biochem. 1988 Aug 1;175(2):271-4. doi: 10.1111/j.1432-1033.1988.tb14193.x.
Rotational dynamics of actin spin-labelled with maleimide probes at the reactive thiol Cys-374 were studied. Replacement of the bound nucleotide by Br8ATP in G-actin and Br8ADP in F-actin causes significant increase of the rotational correlation time of the spin probe, indicating reduced motion in both G and F-actin. The orientation dependence of the electron paramagnetic resonance spectra in oriented F-actin filaments revealed an altered molecular order of the probe when the nucleotide was a Br-substituted one. The bound nucleotide affects the myosin S1 ATPase activation by actin; both Vmax and K(actin) decreased significantly when the bound nucleotide of actin was Br8ADP.
