FLUORIMETRY STUDY OF "N-(1-PYRENYL)IODOACETAMIDE-LABELLED F-ACTIN - LOCAL STRUCTURAL-CHANGE OF ACTIN PROTOMER BOTH ON POLYMERIZATION AND ON BINDING OF HEAVY-MEROMYOSIN

  • 1 January 1981
    • journal article
    • research article
    • Vol. 114  (1) , 33-38
Abstract
A fluorescent reagent, N-(1-pyrenyl)iodoacetamide, was conjugated to rabbit skeletal muscle actin at the site of the most reactive sulfhydryl group. Fluorescence characteristics (excitation and emission spectra, quantum yields, lifetimes) of the conjugate were investigated. Associated with polymerization of labeled G-actin, the fluorescence intensity at 407 nm, after excitation at 365 nm, was enhanced by a factor of .apprx. 25. It was reduced to .apprx. 25% on the binding of heavy meromyosin (or subfragment 1). Binding of heavy meromyosin to the protomer of F-actin apparently alters the local structure of the protomer towards a G-actin-like one.