Question

Bacterial aldolase does not form a Schiff base with the substrate. Instead, it has a divalent Zn²⁺ion in the active site. How does the ionfacilitate the aldolase reaction?

Short answer

The zinc ion polarizes the carboxylic oxygen at the active site of the substrate to stabilize the enolate intermediate of the reaction.

Step-by-step solution

Introduction

Thealdolase process is a glycolysis enzymatic reaction that breaks down glucose into energy. Four amino acid residues make up the active site of aldolase enzyme. Fructose-1, 6-bisphosphate (FBP) aldolase is an enzyme that uses an aldolase process to convert dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP) into FBP.

Ion facilitates the aldolase reaction

An amino group and a carboxylic group are both present in a Schiff base. Because it has a carboxylic group at its active site, bacterial aldolase does not generate a Schiff base with the substrate. Aldolase contains a negative charge at its active site. The reaction is neutralised in this reaction when the divalent Zn²⁺ ion is linked to the active site. To stabilise the enolate intermediate of the process, the Zn²⁺ ion polarises the carboxylic oxygen at the substrate's active site.

Pictorial representation of the Binding of Zn2+ at the active site of the substrate

Interpretation

Thus, to stabilise the enolate intermediate of the reaction, the zinc ion polarisesthe carboxylic oxygen at the substrate's active site.