The pyridoxal phosphate reactivation of the apo form of aspartate aminotransferase (EC 2.6.1.1) in human serum has been studied with "normal" and above-normal activity of this enzyme. The extent of the reactionation did not depend on the presence of the substrates, L-aspartate or 2-oxoglutarate. Reactivation was greatest with 110 mumol of added pyridoxal phsophate present per liter during a pre...

Wolf et al. (1) found little or no serum aspartate aminotransferase (EC 2.6.1.1) activity in the sera of 11 of 19 patients undergoing long-term hemodialysis. The authors concluded that low aminotransferase (transaminase) activities seen in these patients may have been due to loss of the enzyme and (or) to pynidoxine depletion during long-term dialysis. We recently examined the sera of 54 long-t...

The apoenzyme of aspartate aminotransferase formed a stable, active holoenzyme on treatment with pyridoxal in the presence of arsenate.

The primary structure of tyrosine aminotransferase, as deduced from the nucleotide sequence of complementary DNA, was confirmed by fast atom bombardment mass spectrometry of tryptic peptides derived from the purified protein. Limited digestion of the native enzyme with trypsin released an acetylated, amino-terminal peptide; the new amino terminus in the modified enzyme was Val65. Endogenous pro...