Getting the metal right

摘要

Controversy has raged over the identity of the metal cofactor of membrane-bound methane monooxygenase, a methane-oxidizing enzyme. A study suggests that the answer is a cluster of two copper ions.rnEnzymes that catalyse redox reactions often use metal ions to bind and activate substrates, and to carry and distribute electrons. But during the isolation of such an enzyme from its natural source, the metal-containing cofactor can degrade, causing the enzyme to lose activity. Extensively purified enzyme preparations can thus be severely heterogeneous in their cofactor composition. In the worst-case scenario, a minor, undetected form of a purified enzyme can contribute all the catalytic activity.