Transfer of pyridoxal 5'-phosphate from albumin-pyridoxal 5'-phosphate complex to apo-aspartate aminotransferase.

Pyridoxal 5•L-phosphate (PLP) is known to combine with bovine serum albumin to form a(1:1) complex which scarcely dissociates, even when subjected to intensive dialysis. When this complex was incubated with apo-aspartate aminotransferase (apoGOT) for an appropriate time and the preincubated mixture then submitted to the usual GOT assay, the appearance of GOT activity was obviously confirmed, indicating that PLP was transferred from the albumin-PLP complex to apoGOT. The affinity (Km) of the albumin-PLP complex for apoGOT was 1.56ƒÊM. Simultaneous addition of ƒ¿-ketoglutarate to the preincubation mixture decreased markedly the transfer of PLP. Albumin-PLP (1:1) com