A CONTRACTILE PROTEIN FROM THE INTESTINAL WALL

Abstract

1) A contractile protein extracted from the intestinal wall showed superprecipitation at low ionic strength in the presence of Mg⁺⁺ and ATP and it possessed ATPase activity (E. C. 3. 6. 1. 3.). Superprecipitation of the protein was enhanced by an increase of Mg⁺⁺ concentration up to 20mM in a medium and was closely associated with enhancement of ATPase activity of the protein as Mg⁺⁺ concentration increased.
2) The electronmicrogram of the protein showed, at high ionic strength without ATP, an “arrow head” structure characteristic of myosin B from skeletal muscles. This structure disappeared after addition of ATP.
3) It might be concluded that a contractile protein, the so-called actomyosin was observed in the intestinal wall.