L-threonine 3-dehydrogenase

L-threonine 3-dehydrogenase is an enzyme that in humans is encoded by the TDH gene. This enzyme catalyzes the first step in the degradation of threonine, an essential amino acid, converting it to aminoacetone and glycine through a two-step process. Initially, L-threonine is oxidized to 2-amino-3-ketobutyrate, which is then split into aminoacetone and glycine. L-threonine 3-dehydrogenase is a member of the oxidoreductase family, enzymes that catalyze the transfer of electrons from one molecule to another, and plays a crucial role in amino acid metabolism.

Function

L-threonine 3-dehydrogenase plays a pivotal role in the catabolic pathway of threonine. The enzyme is primarily found in the liver and functions in the mitochondria, where it initiates the breakdown of threonine. This process is essential for the body's management of amino acid levels and for energy production. By converting threonine into aminoacetone and glycine, it contributes to the pool of intermediates available for further metabolic processes, including the synthesis of proteins and other vital compounds.

Structure

The enzyme is a protein composed of multiple subunits, each contributing to the enzyme's overall function. The active site of L-threonine 3-dehydrogenase, where the catalytic conversion of L-threonine occurs, is located within a specific region of the protein structure. This site binds threonine and facilitates its dehydrogenation, a reaction that requires the presence of NAD+ (Nicotinamide adenine dinucleotide) as a cofactor. The structural integrity and proper functioning of this enzyme are critical for the efficient metabolism of threonine.

Clinical Significance

Alterations in the activity of L-threonine 3-dehydrogenase can have significant metabolic consequences. Although rare, mutations in the TDH gene that impair the enzyme's function can lead to disorders of amino acid metabolism. These conditions can result in an accumulation of threonine and related metabolites, which may have toxic effects on the body. Understanding the role and mechanics of L-threonine 3-dehydrogenase is crucial for developing therapeutic strategies for such metabolic disorders.

See Also

• Amino acid metabolism
• Oxidoreductase
• Liver
• Mitochondria