Abstract
A crystalline lipase from Aspergillus niger was most severely inactivated by both Fe2+ and Fe3+ among the various metal ions tested. There were two types of inactivation depending on the extent of treatment of the enzyme with Fe ions, a reversible inhibition by a short-time contact with a lower concentration of Fe ions and irreversible inactivation by a longtime treatment with a higher concentration of Fe ions.
The amount of Fe ions bound to the irreversibly inactivated lipase was determined at various inactivation degrees. It was found that the amount of Fe ions bound per mg of the inactivated enzyme protein was constant at any degree of inactivation.
