O-Succinylhomoserine

This enzyme [EC 2.3.1.46], also referred to as homoserine O-transsuccinylase, catalyzes the reaction of succinyl-CoA with homoserine to produce coenzyme A and O-succinylhomoserine. 

Members of at least three bacterial families and all fungi examined utilize O-acetylhomoserine in the cystathionine-homocysteine biosynthetic pathway, whereas several members of the family of enteric bacteria utilize O-succinylhomoserine (Flavin, 1975). The findings now to be discussed establish that green plants use for this purpose yet another O-ester of homoserine, O-phosphohomoserine. 

For the sulfhydration reaction, C>-phosphohomoserine is the most active substrate under assay conditions optimal for activity with this compound. When the activities were determined under conditions optimal for O-acetylhomoserine, activity with O-acetylhomoserine was increased to 17% of that with O-phosphohomoserine, while the relative activity with O-succinylhomoserine remained unchanged. Sulfhydrase activities with O-phosphohomoserine and O-acetylhomoserine showed different patterns of development during early growth of excised barley embryos, suggesting that activities with the two substrates may be catalyzed by separate enzymes (Datko et al., 1977). Purification of these activities will be required to determine whether this suggestion is correct. 

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