Abstract
We estimated lower energy conformers of natural juvenile hormone III (JH III) [methyl-(2E, 6E)-3, 7, 11-trimethyl-(10R, 11)-epoxy-dodecadienoate] based on semi-empirical molecular orbital (MO) MNDO calculations. Conformational analysis by PCILO calculations strongly suggested that JH III possesses an extended conformation and that the two methyl groups at the 3- and 7-positions partially restrict the internal rotations along the carbon chain of dodecadienoate. The same extended conformation was also suggested by phase-sensitive NOESY 2D-NMR measurements. The interatomic distance (L) between the carbonyl carbon and epoxy oxygen atoms and the molecular dimensions of JH III were estimated to be 11.34±0.36Å and 18.5×8.2×7.2 Å, respectively. MNDO calculations, with model enzyme systems, suggested that metabolic oxidation at the (6E)-C=C moiety and hydrolysis both at the ester linkage and epoxide moiety are feasible.
