Background Methanol is produced by fruit during the ripening process. The major

ID: 799723 • Letter: B

Question

Background

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.

Methanol is produced from the action of PME on pectin methyl esters, as described above. The only

route for ethanol production in the plant is the alcohol dehydrogenase-catalyzed reduction of

acetaldehyde to ethanol. Write a balanced equation for the production of ethanol, including structures

and cofactors.

CH3CH2OH + NAD+ ? CH3CHO + NADH + H+

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