D-Glucaric Acid Production via PQQ-ADH and ALDH Enzymes

The patent replaces chemical synthesis methods with biological fermentation methods using genetically modified microorganisms. The microorganisms express specific enzyme combinations (GULO, ALDH2, and ALDH3) to catalyze the conversion of glucose to D-glucaric acid through metabolic pathways, substituting chemical oxidation processes with biological catalysis. This eliminates harmful chemicals and reduces environmental pollution while maintaining production feasibility.

The patent optimizes the enzymatic pathway parameters by selecting specific isoenzymes (ALDH2 and ALDH3) with different kinetic properties and substrate specificities. By controlling the expression levels and activity ratios of these enzymes, the patent achieves high selectivity for D-glucaric acid production while minimizing byproduct formation, thereby reducing production costs and improving environmental sustainability.

The patent employs a multi-enzyme system where GULO converts glucose to L-gulonic acid, ALDH2 oxidizes L-gulonic acid to D-glucaric acid, and ALDH3 oxidizes L-guluronic acid to D-glucaric acid. This multi-functional enzymatic pathway operates under mild physiological conditions while achieving high overall reactivity through the coordinated action of multiple enzymes, each optimized for its specific reaction step.

The patent creates a composite enzymatic system within a single microorganism host, combining multiple enzyme activities (GULO, ALDH2, ALDH3) that work synergistically. This composite enzymatic pathway achieves both mild reaction conditions and high productivity by distributing the catalytic functions across multiple specialized enzymes rather than relying on a single enzyme with compromised performance.