title: Dynamic laser light scattering studies of the effects of pyrophosphate on cyclic motions of cross-bridges in isolated thick myofilaments from Limulus striated muscle.
abstract: Pyrophosphate (PPi) is a non-hydrolyzable ATP analogue known to affect the binding between myosin heads and actin. By using a dynamic laser light scattering method, we have shown that 1-2 mM PPi enhances the increase in gamma values induced by Ca2+ in isolated thick myofilaments from Limulus striated muscle. However, similar treatment has no effect on the gamma values of filaments suspended in either relaxing solution or ATP-free solution. gamma is the average linewidth of the photoelectron count autocorrelation function of the light scattered. PPi had no effect on the increase of gamma values by Sr2+ but it substantially increased the gamma values of the thick myofilaments suspended in Ba(2+)-substituted Ca2+ activating solution. The results show that PPi also affects the energy-requiring cyclic cross-bridge motions.
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Stony Brook 11794.
authors.forename: S F
authors.initials: SF
authors.lastname: Fan
authors.forename: M M
authors.initials: MM
authors.lastname: Dewey
authors.forename: B
authors.initials: B
authors.lastname: Chu
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000187:drug effects; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D006737:Horseshoe Crabs; D007834:Lasers; D008027:Light; D009132:Muscles / Q000187:drug effects / Q000648:ultrastructure*; D015879:Myosin Subfragments / Q000378:metabolism; D010710:Phosphates / Q000494:pharmacology*; D012542:Scattering, Radiation; D013324:Strontium / Q000494:pharmacology
chemical_list: D015879:Myosin Subfragments; D010710:Phosphates; D001464:Barium; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002118:Calcium; D013324:Strontium