The Active Site of Monoamine Oxidase “The Key Enzyme of Biogenic Amines Degradation” as Seen by Magnetic Relaxation Spectroscopy
In the central nervous system, monoamine oxidase (MAO; EC 18.104.22.168) is postulated to be important in controlling the levels of certain neurohormones and other pharmacologically important amines (Sandler et al., 1973; Von Korff, 1979). The potential importance of the enzyme in neuropharmacology has prompted us to explore the nature of the active site by spin labeling techniques. Monoamine oxidase has been characterized by amine substrate specificities and response to inhibitors as having two independent catalytic sites (Tipton et al., 1981; Jani, 1977) or as two distinct enzyme forms (A, B) embedded in the same mitochondrial membrane (White and Tansk, 1979; White and Stine, 1982). Other authors postulated that MAO-A and MAO-B may be the same enzyme in different lipid environments (Huang, 1980; White and Stine, 1982; Fowler and Ross, 1984). The MAO-B which preferentially deaminates benzylamine is sensitive to deprenyl inhbition. Tyramine and tryptamine are substrates for both MAO-A and MAO-B enzymes (Tipton et al., 1976; Oreland and Eksted, 1976). Many of the complex problems surrounding the mechanism of action, regulation and substrate specificity of mitochondrial MAO have resisted definitive resolution when explained by traditional enzymological approaches. We have been exploring the utility of spin labels in studying these problems.
KeywordsElectron Spin Resonance Electron Spin Resonance Spectrum Monoamine Oxidase Electron Spin Resonance Signal Spin Label
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