Effect of Diazonium Derivatives on Myosin A Adenosine Triphosphatase

I. Effect of Diazobenzene-p-sulfonate Modification on the Activation of Myosin A ATPase by Activators

Abstract

1. Coupling of myosin A with diazobenzene-p-sulfonic acid in-hibited the EDTA-ATPase activity without any essential change in activity or catalytic properties of Ca⁺⁺-ATPase. The coupling also selectively diminished the allosteric action of other effectors, DNP and NEM.
2. Ionic strength, pH and substrate or its analogues had little or no effect on azo coupling of myosin with DBS.
3. It was concluded from spectrophotometric comparison of azo-myosin with azo amino acids and from other experimental results that the sulfhydryl residues in the active site of myosin had reacted with DBS.