Draw the mechanism for the hydroxide ion–catalyzed cleavage of fructose-1,6-bisphosphate.

Verified step by step guidance

1. Identify the functional groups in fructose-1,6-bisphosphate that are susceptible to nucleophilic attack by the hydroxide ion (OH⁻). Focus on the phosphate ester linkages.
2. Recognize that the hydroxide ion acts as a nucleophile and will attack the electrophilic phosphorus atom in one of the phosphate groups, leading to the formation of a pentavalent transition state.
3. Following the nucleophilic attack, the transition state collapses, resulting in the cleavage of the P-O bond and the release of a phosphate ion. This step is facilitated by the leaving group ability of the phosphate.
4. Consider the stabilization of the resulting carbanion intermediate by resonance or other structural features of the molecule.
5. Protonation of the carbanion intermediate by water or another proton donor in the solution leads to the formation of the final products, completing the cleavage mechanism.

Key Concepts

Mechanism of Enzyme-Catalyzed Reactions

Enzyme-catalyzed reactions often involve a series of steps where substrates are transformed into products through intermediate states. Understanding the mechanism requires knowledge of how enzymes lower activation energy and stabilize transition states, facilitating the conversion of substrates. In the case of fructose-1,6-bisphosphate, the hydroxide ion acts as a catalyst, promoting the cleavage of the molecule.

Role of Hydroxide Ion

The hydroxide ion (OH-) is a strong nucleophile that can attack electrophilic centers in organic molecules. In the context of the cleavage of fructose-1,6-bisphosphate, the hydroxide ion facilitates the breaking of the phosphate ester bond by attacking the carbon atom bonded to the phosphate group. This nucleophilic attack is crucial for the reaction mechanism and leads to the formation of the cleavage products.

Fructose-1,6-bisphosphate Structure and Function

Fructose-1,6-bisphosphate is a key intermediate in glycolysis, consisting of a fructose sugar with two phosphate groups attached. Its structure is essential for understanding its reactivity and the specific sites where enzymatic cleavage occurs. Recognizing the functional groups and their positions helps in visualizing the mechanism of cleavage and the role of hydroxide in the reaction.