Question: Methanol is produced by fruit during the ripening process. The major source of this methanol is l…

Methanol is produced by fruit during
the ripening process. The major source of this methanol is likely
to be

from the enzyme pectin methylesterase
(PME) which acts upon pectin methyl esters to de-esterify them and
produce methanol and other pectic substances. One might assume that
the production of methanol is correlated with PME activity, but
this has not been firmly established. In this case, the
investigators at the Plant Science Department at Rutgers University
developed a transgenic tomato which was deficient in PME
activity. By comparing the behavior
of the transgenic tomato with the wild type tomato, the production
of methanol in the ripening tomato fruit may be better
understood.

The
investigators measured PME enzyme activity in immature green (IMG),
mature green (MG), breaker (Br), turning (Tu) and red ripe (RR)
tomatoes. They also determined the amount of PME protein present by
using a Western blot assay, which uses a specific antibody to
detect the PME protein. The results are shown in Figure
12.1.

What is your interpretation of these
results?