Neryl pyrophosphate, rather than geranyl pyrophosphate, is
believed to be the immediate biological precursor of the cyclohexanoid
monoterpenes because the cis-2, 3-double bond readily permits cyclization.
Biosynthesis of neryl pyrophosphate could occur by either of
two principal mechanisms: direct cis condensation of dimethylallyl
pyrophosphate with isopentenyl pyrophosphate or trans-cis isomerization...
Isomerically pure cis,cis,trans-1-pheny1-1,3,5-
heptatriene was prepared and cyclized. Ring closure
was followed by a 1,5 hydrogen shift, and the only product
observed was 1-phenyl -6-methyl -1,3-cyclohexadiene.
Rough first order rate constants for thermolysis and
the hydrogen shift were determined. Kinetic estimates
indicate that the report of disallowed product in a...
Conversion of exogenous cis-zeatin to trans-zeatin in immature seeds of
Phaseolus vulgaris L. led to the isolation of a cis-trans isomerase from the endosperm.
The enzyme was purified over 2000-fold by chromatography on a series of FPLC
(anion exchange, gel filtration, and hydrophobic interaction) and Concanavalin A
columns. Non-enzymatic isomerization...