Organisms contain many different kinds of transaminases, all of which require pyridoxal phosphate (avitamin B6 derivative) as a coenzyme (Figure 16.7). (See the Looking Deeper-Pyridoxal Phosphate and Transaminases.) Although most transamimases use α-ketoglutarate/glutamate as one of the amino group acceptor/donor couples, they differ in their specificity toward the second acceptor/donor couple. Individual transaminases are named according to this specificity. For example, both alanine transaminase and aspartate transaminase use α-ketoglutarate/glutamate as one of the amino group acceptor/donor couples (Figure 16.8). However, alanine transaminase uses pyruvate/alanine as the second acceptor/donor couple, whereas aspartate transaminase uses the oxaloacetate/aspartate couple.