Methods Used to Reversibly Resolve Flavoproteins into the Constituents Apoflavoprotein and Prosthetic Group

There are two classes of flavoproteins with respect to the interaction between the apoflavoprotein and its prosthetic group. In one class, the flavin is often tightly, but noncovalently bound. In the other class, the interaction between the two components is of covalent nature, the flavin being attached to an amino acid residue. This chapter discusses the most commonly used procedures for the preparation of apoflavoproteins. Although the development of methods for the reversible resolution of flavoproteins can be tedious and time consuming, especially when the goal is the achievement of a high reconstitutability, some studies should be included in the basic work done to characterize a new flavoprotein. Although the covalent chromatography method could be applied to any flavoprotein possessing an easily accessible sulfhydryl group, the method probably does not always give satisfactory results. The acid ammonium sulfate treatment is a rapid method to probe the possible preparation and stability/reconstitutability of apoflavoproteins on an analytical scale.