Abstract
The properties of a purified β-cyanoalanine (β-CNAla)-forming enzyme isolated from Enterobacter sp. 10-1 were studied.
It has been found previously that this enzyme catalyzed the formation of cysteine from O-acetyl-L-serine and soldium sulfide, as well as the formation of β-CNAla from O-acetyl-L-serine and sodium cyanide.
The affinity of the enzyme for sodium sulfide in the formation of cysteine was one order of magnitude greater than that for sodium cyanide in the β-CNAla formation. In addition, the optimum pH, pH- and thermal stability of β-CNAla-forming activity were similar to those of cysteine-forming activity. The results of the studies indicated that the β-CNAla-forming enzyme of Enterobacter sp. 10-1 was an O-acetylserine sulfhydrylase catalyzing the formation of cysteine from O-acetyl-L-serine and sulfide. The solution of the enzyme was yellow and exhibited an absorption peak at 420 nm. The enzyme itself contained approximately 1 mol of pyridoxal phosphate per 34, 000 g of protein.
