Enzyme activity of macrophage migration inhibitory factor toward oxidized catecholamines

Macrophage migration inhibitory factor (MIF) is a relatively small, 12.5-kD a protein that is structurally related to some isomerases and for which mul tiple immune and catalytic roles have been proposed. MIF is widely expresse d in tissues with particularly high levels in neural tissues. Here we show that MIF is able to catalyze the conversion of 3,4-dihydroxyphenylaminechro me and norepinephrinechrome, toxic quinone products of the neurotransmitter catecholamines 3,4-dihydroxyphenylamine and norepinephrine, to indoledihyd roxy derivatives that may serve as precursors to neuromelanin. This raises the possibility that MIF participates in a detoxification pathway for catec holamine products and could therefore have a protective role in neural tiss ues, which as in Parkinson's disease, may be subject to catecholamine-relat ed cell death.