Abstract
Pyridoxal enzymes catalyze versatile reactions with amino acids, including transamination, recemization, α, β-elimination, and decarboxylation. The reaction mechanism for these reactions has been explained on the basis of diverse chemical properties of pyridoxal phosphate. Recent progress in recombinant DNA techniques allowed us to examine the role of apoproteins of the pyridoxal enzymes at the atomic level based on crystallographic and sitedirected mutagenesis studies. Among the pyridoxal enzymes, aminotransferases, particularly aspartate aminotransferase, have been most extensively studied from structural and functional aspects. In this paper, I will describe some important information obtained recently on substrate recognition and transaldimination, which are the initial steps common to all the pyridoxal enzymes, centering discussion on the uniqueness of aspartate aminotransferase.
