Molecular geometries and steric energies of phorbol 10,11-diacetate and 1,2-diacetylglycerol molecules.

Protein kinase C, an enzyme that is stimulated physiologically by diacylglycerol (DAG) and phospholipids in the presence of Ca2+, is involved in a novel cellular signaling system that is activated by the binding of appropriate agonists to certain classes of receptors. Phorbol esters are tumor promoters that can replace DAG in the activation of protein kinase C. Molecular similarities between the two compounds have been proposed to be responsible for the capacity to activate the enzyme. We have studied the molecular geometries and conformational energies of DAGAc and PDAc using the Molecular Mechanics II program and parameter set developed by Allinger and Yuh (1980). This was done to establish whether conformers of the two compounds are geometrically similar and which hydroxyl group of the phorbol molecule corresponds to the C3 hydroxyl of DAG which must be unsubstituted for activation of protein kinase C.