SYNTHESIS OF O-ACETYLSERINE BY EXTRACTS PREPARED FROM HIGHER PLANTS

This communication describes a novel plant enzyme, which catalyzes the formation of O-acetylserine from serine in the presence of S-acetylCoA. The enzyme activity was shown to be present in both the particulate and soluble fractions of a range of plant seedlings and leaves. The enzymatic synthesis of cysteine from O-acetylserine and sulfide (reaction 1) has been reported in Escherichia coli, yeast, and Neurospora, (Wiebers and Garner, 1967). O-acetylserine +sulfide → cysteine + acetate (1) Cysteine synthase present in higher plant extracts also apparently utilizes O-acetylserine more readily than serine as a sulfide acceptor (Giovanelli and Mudd, 1967, 1968; Thompson and Moore, 1968). An enzyme, serine acetylase, which catalyzes the acetylation of serine (reaction 2) has been reported in bacteria (Kredich and Tomkins, 1966). S-acetylCoA + serine → O-acetylserine +CoASH (2). The present communication reports the occurrence of serine acetylase in higher plant extracts. © 1969.