(S)-3-amino-2-methylpropionate transaminase () is an enzyme that catalyzes the reversible chemical reaction
The two substrates of this enzyme characterised from kidney and liver are (S)-3-aminoisobutyric acid and α-ketoglutaric acid. Its products are 3(S)-methylmalonaldehydic acid and L-glutamic acid.
This enzyme is a transferase, specifically a transaminase, which transfer nitrogenous groups. The systematic name of this enzyme class is (S)-3-amino-2-methylpropanoate:2-oxoglutarate aminotransferase. Other names in common use include L-3-aminoisobutyrate transaminase, beta-aminobutyric transaminase, L-3-aminoisobutyric aminotransferase, and beta-aminoisobutyrate-alpha-ketoglutarate transaminase. It participates in valine, leucine and isoleucine degradation.
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