Chapter 16, Problem 16.55UTC

Interpretation Introduction

To determine:

1. The class of enzyme that catalyzes the reaction.
2. Preventing toxic level of oxalic acid in the body by the ingestion of solution of ethanol in the body.

Answer to Problem 16.55UTC

Solution:

1. Class of enzyme that catalyzes the reaction: Oxidoreductase.

The cytochrome P-450 enzyme and alcohol dehydrogenase usually denoted by ADH are the class of enzymes which catalyze the reaction.

2. The treatment for the ingestion of ethylene glycol is an intravenous solution of ethanol as it has much higher affinity for the alcohol dehydrogenase, the first enzyme in the degradation pathway there by blocking the formation of subsequent products.

Given:

Ethylene glycol ( ${\text{HO-CH}}_{\text{2}}{\text{-CH}}_{\text{2}}\text{-OH}$ ) is added to radiator to prevent freezing and boiling. If ingested, it gets converted first to oxoethanoic acid, $\text{HOOC-CHO}$ and then to oxalic acid, $\text{HOOC-COOH}$ , which is toxic.

Treatment of ethylene glycol is an intravenous solution of ethanol.

Explanation of Solution

1. Ethylene glycol on oxidation gives oxoethanoic acid and oxalic acid. So, this reaction is catalyzed by oxidase enzyme which belongs to the class of oxidoreductase.

The alcohol dehydrogenase enzyme also denoted by ADH is the enzyme that convert/ catalyze the reaction ethylene glycol to glycolaldehyde there by making it toxic.

2. Ethanol of pharmaceutical grade is given intravenously to prevent the formation of oxalic acid. This is because the toxicity of ethylene glycol comes from the formation of oxalic acid and glycolic acid. The formation of these can be prevented by addition of alcohol as alcohol is found to have much higher affinity to alcohol dehydrogenase compared to ethyl glycol which helps in preventing the degradation of ethylene glycol. If the oxalic acid formation is prevented the body excretes the ethylene glycol out.

Conclusion

1. Class of enzyme that catalyzes the reaction: Oxidoreductase.

The cytochrome P-450 enzyme and alcohol dehydrogenase usually denoted by ADH are the class of enzymes which catalyze the reaction.

2. The treatment for the ingestion of ethylene glycol is an intravenous solution of ethanol as it has much higher affinity for the alcohol dehydrogenase, the first enzyme in the degradation pathway there by blocking the formation of subsequent products.