An appreciation of Professor Alexander E. Braunstein. The discovery and scope of enzymatic transamination

Nonenzymatic transamination was discovered in the early 1930s. In the mid-1930s Braunstein and associates discovered the process of enzymatic transamination and established the biological significance of this reaction. Over the next 50 years, Braunstein and coworkers continued to contribute many new ideas and make important discoveries in the field of aminotransferases and other pyridoxal 5'-phosphate enzymes. This review outlines (1) the events leading to the discovery of enzymatic transamination, (2) how the discovery was made, (3) the findings that led to the recognition by the mid-1950s of the very wide scope and biological importance of aminotransferase reactions, and (4) the elucidation of the primary amino acid sequence and three-dimensional structure of aspartate aminotransferases.