Demonstration of adenosine triphosphate hydrolysis in the enamel organ of the mouse incisor

The hydrolysis of adenosine triphosphate in the mandibular enamel organ demonstrated that the Mg⁺⁺ activated ATPase was destroyed by pretreatment with either heat or alcohol, substrate specific for ATP, stimulated by the addition of glutathione or dinitrophenol, and inhibited by oligomycin. The distribution of reaction product was the same with Mg⁺⁺, Mn⁺⁺ or Zn⁺⁺ as the activating cation. Omission of Mg⁺⁺ from the incubation medium, or replacement with Ca⁺⁺ or Sr⁺⁺ resulted in marked hydrolysis of ATP in the cells associated with enamel matrix formation, with loss of enzyme activity in the cells of the zone of enamel matrix maturation. Hydrolysis of ATP by the cells of the stratum intermedium, stellate reticulum and papillary layer was dependent upon Mg⁺⁺, Mn⁺⁺, or Zn⁺⁺.