Glyoxylat

Glyoxylat, or glyoxylate, is the two‑carbon organic anion derived from glyoxylic acid. It contains an aldehyde group and a carboxylate group, and at physiological pH it exists mainly as the glyoxylate anion or as salts of the acid. As a reactive metabolic intermediate, glyoxylate participates in several cellular pathways and environmental processes.

In biology, glyoxylate is best known as a key intermediate of the glyoxylate cycle, a carbon-conserving variant of the tricarboxylic acid (TCA) cycle found in plants, some bacteria, and fungi. In this pathway, isocitrate lyase cleaves isocitrate to produce succinate and glyoxylate; glyoxylate then combines with acetyl‑CoA through malate synthase to form malate. Malate can be converted to oxaloacetate, allowing organisms to convert two‑carbon units into four‑carbon compounds and enabling gluconeogenesis under conditions where acetyl‑CoA is the primary carbon source.

Glyoxylate also arises in plant photorespiration, where glycolate oxidation generates glyoxylate. It can be transaminated by glyoxylate aminotransferase to form glycine, linking photorespiration to amino acid metabolism. In animals, the glyoxylate cycle is not complete, but glyoxylate is produced and detoxified by enzymes such as glyoxylate reductase and related activities to minimize accumulation that could be harmful.

Commercially, glyoxylate and its salts are used as chemical intermediates in organic synthesis and as research reagents. Handling requires appropriate precautions due to its reactive aldehyde functionality and potential irritant effects.

Overall, glyoxylate is a small but important metabolic and chemical intermediate with roles in carbon allocation, amino acid metabolism, and plant physiology.