Microbial aldolases as C-C bonding enzymes--unknown treasures and new developments

Anne K Samland1, Georg A Sprenger

  • 1Institut für Mikrobiologie, Universität Stuttgart, Germany.

Summary

Aldolases are enzymes that create carbon-carbon bonds, valuable for synthesizing complex molecules like rare sugars. Microbial aldolases offer diverse applications in asymmetric synthesis and chemoenzymatic chemistry.

Related Concept Videos

C–C Bond Formation: Aldol Condensation Overview01:10

C–C Bond Formation: Aldol Condensation Overview

Aldol condensation is an important route in synthetic organic chemistry used to generate a new carbon–carbon bond under basic or acidic conditions. The aldol condensation reaction presented in Figure 1 constitutes an aldol addition reaction followed by the dehydration process.
C–C Bond Cleavage: Retro-Aldol Reaction00:57

C–C Bond Cleavage: Retro-Aldol Reaction

The reverse of the aldol addition reaction is called the retro-aldol reaction. Here, the carbon–carbon bond in the aldol product is cleaved under acidic or basic conditions to form two molecules of carbonyl compounds. The mechanism of the reaction consists of three steps.
In the first step, as depicted in Figure 1, the base deprotonates the β-hydroxy ketone at the hydroxyl group to form an alkoxide ion.
Acid-Catalyzed Aldol Addition Reaction01:15

Acid-Catalyzed Aldol Addition Reaction

The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The acid-catalyzed aldol reaction is depicted in Figure 1.
Dehydration of Aldols to Enals: Base-Catalyzed Aldol Condensation01:14

Dehydration of Aldols to Enals: Base-Catalyzed Aldol Condensation

This lesson delves into the aldol condensation catalyzed by bases, where aldols undergo dehydration to enals. As shown in Figure 1, the β-hydroxy aldehyde formed in a base-catalyzed aldol addition reaction dehydrates on heating to yield an unsaturated carbonyl product, which is commonly referred to as an enal.
Base-Catalyzed Aldol Addition Reaction01:08

Base-Catalyzed Aldol Addition Reaction

As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy carbonyl compound.