Preparative separation of alpha- and beta-naphthols catalyzed by immobilized sulfatase.
It has been found that sulfatase from Helix pomatia hydrolyzes beta-naphthyl sulfate much faster than alpha-naphthyl sulfate; e.g., at pH 7.8, while the former is readily hydrolyzed, the latter undergoes no appreciable hydrolysis. Kinetic investigations of both enzymatic and acid hydrolysis of naphthyl sulfates and their analogs indicate that in the enzymatic reaction the difference in reactivities is due to steric hindrances exerted in alpha-naphthyl sulfate by the benzene ring adjacent to the one bearing the sulfate group. (In the beta-ester this ring is remote from the site of hydrolysis.) The enzyme was immobilized and employed for the preparative resolution of alpha- and beta-naphthols: a mixture of the isomers was first sulfated with chlorosulfonic acid and then incubated with sulfatase covalently attached to alumina. The beta-naphthol produced was extracted with benzene, followed by acid hydrolysis of alpha-naphthyl sulfate in the remaining aqueous solution and extraction of the alpha-naphthol formed. Helix pomatia sulfatase also expresses a marked regiospecificity in the hydrolysis of ortho and para substituted phenyl sulfates. Therefore, the enzyme can be used for the preparative separation of naphthols as well as a variety of isomeric phenols.
Laboratory of Applied Biochemistry, Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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Pelsy
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Klibanov