9] Preparation of metal-hybrid enzymes

Abstract

Publisher Summary This chapter discusses various methods for the preparation of metal-hybrid enzymes. Three approaches exist for metal exchange: (1) preparation of an apoenzyme with subsequent insertion of a metal ion, (2) displacement of the intrinsic metal ion by another metal ion (sometimes referred to as interchange or direct exchange), and (3) growth of a micro-organism producing the metalloenzymes in a medium, in which the concentration of the native metal ion is very low and the concentration of the metal ion to be incorporated is relatively high. This biosynthetic incorporation of metal ions does not necessarily provide selectivity, since it will most probably produce a fully metal-substituted species. Only the remaining two approaches are suited for the preparation of metal-hybrid enzymes. Upon selective removal of a fraction of metal ions from metalloproteins partially metal-depleted apoenzyme arc formed. When two metal ions per protein arc are present, the latter have been designated as half-apoenzyme.