Studies on the amino groups of myosin-ATPase. II. Localization of the amino groups.

1-5 of the epsilon-amino groups of myosin were trinitrophenylated by 2,4,6-trinitrobenzene sulphonate. The Mg2+-activated ATPase activity was found to increase twenty fold while the K+-activated ATPase was strongly inhibited as a result of this treatment. Myosin was dissociated by urea after trinitrophenylation and its heavy and light chains were isolated. Virtually all the introduced trinitrophenyl groups were found in the heavy chain indicating that the lysyl residues, the modification of which affects the ATPase activity, are located at the heavy core of the myosin molecule.