The interaction of dopamine-beta-hydroxylase with concanavalin A and its use in enzyme purification

Dopamine-β-hydroxylase forms a complex with concanavalin A and can be quantitatively dissociated from the complex with α-methyl-D mannoside. It can thus be separated from other chromaffin vesicle proteins that have no affinity for the lectin. Using this observation it was possible to purify the enzyme by a single passage through a column of concanavalin A-Sepharose. Analysis of the concentrated eluate by disc gel electrophoresis showed that the dopamine-β-hydroxy-last was 93% pure. The binding of this glycoprotein enzyme to concanavalin A indicates that the polysaccharide moiety is highly branched and contains α-D-mannopyranosyl and/or α-D-glucopyranosyl residues as the terminal sugars.