Affinity Methods for the Purification of Arylsulphatase A
Arylsulphatases (arylsulphate sulfohydrolases, E.C. 22.214.171.124.) A (sulphatase A) and B (sulphatase B) hydrolyse p.nitrocatecholsulphate (p.NCS). Only sulphatase A hydrolyses sulphatides (1).This enzyme is found in all maumialian tissues; its absence in humans is responsible for metachromatic leukodystrophy (MLD). It can be separated by polyacrylamide gel electrophoresis into two isoenzymes (2) which are both absent in the classical form of MLD, but a variant of this disease has been found (3) where only one of the two isoenzymes is lacking. In view of the involvement of the sulphatase A in these different variants of sulphatidoses, it seems of importance to develop a simple procedure, allowing thereafter the investigation of small quantities of pathological material. The enzyme has been already purified from ox liver (4), from human liver (5, 6, 7) and from various other sources. Most of the procedures described are long and involve numerous steps, using physicochemical properties of the enzyme. They require salt precipitations, ion exchange columns, gel filtration and isoelectric focussing. The affinity of the enzyme for concanavalin A has been reported by Bishayee & Bachhawat (8) who have obtained a 16-fold purification for this step alone in sheep brain. An affinity chromatography method has been tried (9) with psychosine sulfate, a component of the natural substrate of sulphatase A, as a ligand, but gave only a 2-fold purification. Agogbua & Wynn (10) have reported a derivative of p.nitrocatechol-sulphate as an affinity ligand which specifically binds sulphatase B; under the conditions they described, sulphatase A was not adsorbed.
KeywordsCarbodiimide Hydrochloride Metachromatic Leukodystrophy Crude Homogenate Phase Filter Methyl Glucoside
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