Effects of Pyridoxal 5'-Phosphate on the Refolding of Aspartate Aminotransferase

Abstract

The effects of pyridoxal 5'-phosphate on the refolding of aspartate aminotransferase were studied. The refolding of the cytoplasmic isozyme of pig heart aspartate aminotransferase denatured with 6 M guanidine hydrochloride depends critically on the presence of pyridoxal 5'-phosphate. Pyridoxal 5'-phosphate affects a refolding intermediate at guanidine hydrochloride concentrations between 3.5 and 2.0 M to bring out the correct folding. In contrast, thermostable aspartate aminotransferase of Bacillus sp. YM-2 can be refolded independently of pyridoxal 5'-phosphate.