Liver alcohol dehydrogenase (ADH) is relatively nonspecific and will oxidize ethanol or other alcohols, including methanol. Methanol oxidation yields formaldehyde, which is quite toxic, causing among other things, blindness. Mistaking it for the cheap wine he usually prefers with his dinner, my dog Sam-E ingested about 125 mL of windshield washer fluid (solution containing 75.0 % methanol). Knowing that methanol would be excreted eventually by Sam-E's kidneys if its oxidation could be blocked, and realizing that, in terms of methanol oxidation by ADH, ethanol would act as a competitive inhibitor, I decided to offer Sam-E some brandy. How much of my favorite Mosel River area vintage (35.0 % ethanol) brandy must Sam-E consume in order to lower the activity of his ADH on methanol to 2.00% of Vmax?
The Km values of canine ADH for ethanol and methanol are 2.25 mM and 150.0 mM respectively. The KI for ethanol in its role as a competitive inhibitor of methanol oxidation by ADH is the same as its Km. Both the methanol and ethanol will quickly distribute throughout Sam-E's body fluids, which amount to about 12.0 L. Assume the densities of the 75.0% methanol and the brandy are both 1.00 g/mL.