4,4'-Bis (1-anilinonaphthalene 8-sulfonate) (bis-ANS): a new probe of the active site of myosin.

Abstract

The interaction of [rabbit skeletal muscle] myosin subfragment-1 (S-1) with bis-ANS was studied by monitoring the fluorescence of the latter when the 2 components formed a complex. Because ATP and ATP analogs partially displaced complexed bis-ANS it was also possible to study interactions of S-1 and nucleotides by using the displacement effect. Approximate values of the parameters of these various interactions were measured. Some possible applications of bis-ANS were explored. It provided a very convenient method of obtaining the Km in steady-state S-1 nucleoside triphosphatase; this particular application also provided some evidence for inferring that in Ca2+ (but not in Mg2+) ATPase (ATP phosphohydrolase, EC 3.6.1.3) S-1 behaved like a mixture of 2 components, each with its own Km. Clear energy transfer occurred between tryptophan residues and bound bis-ANS. S-1 underwent some slow relaxations following substrate binding.