New glucose isomerase having altered optimum ph

PURPOSE: To obtain the subject new enzyme having a part of amino acid different from a wild enzyme, an altered optimum pH, especially having an optimum pH at a lower acidity side and degradable starch at a low pH by manifesting a gene encoding its metalloenzyme. CONSTITUTION: This new glucose isomerase of a mutant metalloenzyme obtained by manifesting a gene encoding its metalloenzyme, having at least an amino acid different from a wild enzyme and exhibiting an altered pH-activation profile by preparing a DNA sequence encoding glucose isomerase, mutating the sequence at a selected nucleotide position, cloning the resultant mutated sequence so that a DNA sequence is manifested in a manifestation vector, transforming the resultant manifestation vector by introducing it into a host organism or cell composed of a microorganism (e.g. Actinoplanes missouriensis) belonging to family Actinomycetales, culturing the transformed host organism in a medium and isolating the product from the cultured material. COPYRIGHT: (C)1994,JPO