Serine palmitoyltransferase, which is one of the alpha-oxamine synthase family enzymes, catalyzes the condensation reaction of L-serine and palmitoyl-CoA to form 3-ketodihydrosphingosine, the first and rate-determining step of the sphingolipid biosynthesis. As with other alpha-oxamine synthase family enzymes, the catalytic reaction is composed of multiple elementary steps, and the mechanism to control these steps to avoid side reactions has been the subject of intensive research in recent years. Combined spectroscopic, kinetic, and structural studies have revealed the finely controlled stereochemical mechanism, in which the His residue conserved among the alpha-oxamine synthase family enzymes plays a central and critical role. This article is part of a Special Issue entitled: Pyridoxal Phosphate Enzymology. (C) 2011 Elsevier B.V. All rights reserved.