Insoluble complexes of amino-acids, peptides, and enzymes with metal hydroxides

Abstract

Investigation of a number of gelatinous metal hydroxides has established that several (e.g. those formed from Ti^IV, Zr^IV, Fe^III, V^III, and Sn^II) are capable of forming with enzymes insoluble complexes which are enzymically active. From the practical viewpoint Ti^IV and Zr^IV proved the most satisfactory. Comparatively high retentions of enzyme specific activity may be achieved. Complexes of these metal hydroxides may also be formed with peptides and amino-acids. All these complexes are considered to be formed by the re-occupation of ligand sites on the metal ions by the incoming molecules. The metal hydroxide–amino-acid complexes can also subsequently bind an enzyme molecule, to give a product the pH–activity profile of which may differ from that of the soluble form of the enzyme. Thus by this technique it may be possible to alter the pH optimum of an enzyme. The peptide ligand can be displaced from the complex by phosphate or fluoride ions, or by any other such entity capable of forming a more stable complex with the metal ion involved.