ketoacids

Ketoacids, commonly referred to as alpha-keto acids, are a class of organic compounds that contain a ketone group directly adjacent to a carboxyl group. This arrangement makes them 2-oxo carboxylic acids. The core feature is the ketone on the alpha carbon relative to the carboxyl group. A simple example is pyruvic acid, CH3-CO-COOH, a central metabolite in energy production.

Common examples include pyruvic acid, oxaloacetic acid (found in the citric acid cycle and gluconeogenesis), and alpha-ketoglutaric acid (a key intermediate in the citric acid cycle). These compounds are often produced or interconverted during amino acid catabolism, where transaminase enzymes transfer amino groups to or from alpha-keto acids, shaping the pool of metabolic intermediates.

Biological roles and metabolism

Alpha-keto acids act as hubs connecting carbohydrate and amino acid metabolism. Pyruvate links glycolysis to the TCA cycle, and can be converted to acetyl-CoA by pyruvate dehydrogenase for energy production. Oxaloacetate and alpha-ketoglutarate are essential TCA cycle intermediates that also serve as carbon skeletons for biosynthesis and as acceptors in transamination reactions. Cells can replenish TCA cycle intermediates through anaplerosis, for example by carboxylating pyruvate to oxaloacetate.

Reactivity and applications

In biochemistry, alpha-keto acids readily undergo transamination, oxidative decarboxylation, and other enzyme-catalyzed transformations. They also occur as intermediates in various catabolic and biosynthetic pathways and are used as substrates and metabolic probes in research and biotechnology.