BOVINE ADRENAL MEDULLARY DOPAMINE‐β‐HYDROXYLASE: STUDIES ON INTERACTION WITH CONCANAVALIN A

Bovine adrenal medullary dopamine‐β‐hydroxylase binds with concanavalin A and forms an enzymically active precipitate. The formation of the insoluble complex is pH‐dependent and can be inhibited by α‐methyl‐D‐mannoside, D‐mannose and D‐glucose. The insoluble complex can be dissociated into two species with α‐methyl‐D‐mannoside. From the results, it appears that the interaction between dopamine‐β‐hydroxylase and concanavalin A is due to the carbohydrate moiety of dopamine‐β‐hydroxylase. This property was used to purify the enzyme from a soluble lysate of chromaffin granules. Of all the proteins contained in the soluble lysate, dopamine‐β‐hydroxylase was the only one to be retained on a column of concanavalin A covalently bound to Sepharose 4B. The preparation of pure dopamine‐β‐hydroxylase exhibits a very high specific activity of 320 μmol of octopamine formed per 30 min per mg of protein.