Autar K. Mattoo, 
James E. Baker, 
Edo Chalutz, 
Morris Lieberman

Arrhenius plots of ethylene-synthesizing systems of apple and tomato showed discontinuities while the plot for Penicillium digitatum was linear. Triton X-100 markedly lowered the activation energies of the apple and tomato systems without altering that of the fungal system. The data presented suggest that the lipid micro-environment of the ethylene-synthesizing enzyme systems in higher plants and P. digitatum are different, and that cell membrane-cell wall complex may be the site of ethylene-synthesizing enzymic systems in higher plants.