title: Nuclear magnetic resonance studies of D2O-substrate exchange reactions catalyzed by glutamic pyruvic and glutamic oxaloacetic transaminases.
abstract: Nuclear magnetic resonance studies in D2O (greater than 90%) with glutamic pyruvate transaminase (GTP) (2.6.1.2) demonstrate that this enzyme catalyzes the rapid exchange of both the alpha and beta hydrogens of L-alanine, the exchange of only one alpha hydrogen of glycine, and the beta hydrogens of pyruvate and fluoropyruvate. When the beta hydrogens of L-alanine undergo the enzyme-catalyzed exchange, the product may have 1, 2 or 3 of beta hydrogens exchanged. The exchange is stimulated by the addition of catalytic  amounts of copartner of transaminations reaction. A mechanism is proposed for an extension of the conjugated system to include the alpha and beta carbons to explain the labilization of the beta hydrogens.
mesh_terms: D000409:Alanine / Q000378:metabolism; D003903:Deuterium / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy
chemical_list: D003903:Deuterium; D000409:Alanine