FUNCTIONAL CONVERSION OF MYOGLOBIN BOUND TO SYNTHETIC BILAYER-MEMBRANES - FROM DIOXYGEN STORAGE PROTEIN TO REDOX ENZYME

Myoglobin (Mb), a water-soluble hemoprotein, is effectively organized together with NADH and FMN coenzymes on the surface of aqueous synthetic bilayer membranes. The redox activity and the binding mode of membrane-bound Mb molecules were studied by UV-visible and ESR spectroscopies and the ultrafiltration binding assay. Mb molecules bound onto a mixed bilayer of ammonium (1) and phosphate (2) amphiphiles can efficiently accept an electron from NADH via FMN and subsequently release its electron catalytically to dioxygen and 1,2-naphthoquinone-4-sulfonate. Thus, Mb is converted from an oxygen storage protein to a redox enzyme. ESR examination of a cast film of the aqueous mixture indicates that Mb is bound to the mixed bilayer in a precision comparable to conventional membrane-bound enzymes. Implications of the present methodology were discussed in terms of functional conversion of enzymes and design of novel multienzyme systems.