NOVELTY - A diaphorase comprising polypeptide chosen from (a) polypeptide comprising amino acid sequence of SEQ ID NO: 1, (b) polypeptide comprising amino acid sequence in which one or more amino acid residue are substituted, deleted, inserted, added and/or inverted in the SEQ ID NO: 1, and (c) polypeptide comprising amino acid sequence having 80% or more sequence homology with the amino acid sequence of the SEQ ID NO: 1, is new. Sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication.    USE - The diaphorase is useful for clinical diagnosis drug and industrial utilization for measuring glucose level in all the samples (e.g. blood and foodstuffs including seasoning and drinks) containing NADH, and as enzyme electrode, enzyme sensor, and enzyme battery in fuel cell.    ADVANTAGE - The diaphorase has subunit molecular weight measured by sodium dodecyl sulfate-polyacrylamide electrophoresis of 23.7 kDa, composite molecular weight measured by gel filtration of 53.3 kDa, Km value value with respect to NADH of 0.1 mM or less, temperature stability at 70 degrees C or less, pH stability at 5-9, specific activity of 100% in presence of 20 mM NADH, specific activity of 50% in presence of 80 mM NADH and activity of 100% at 37 degrees C and relative activity of 70% or more at 25 degrees C while using dichlorophenolindophenol or naphthoquinone derivative as mediator, exhibits 1.5 times or more specific activity as compared to existing wild-type diaphorase, requires in minimal amount, can be immobilized to sensor strip having high temperature, is stable, and provides lifetime and electromotive force while applying to fuel cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) DNA chosen from (a) DNA encoding amino acid sequence of the SEQ ID NO: 1, (b) DNA comprising base pair sequence of SEQ ID NO: 2, (c) DNA encoding polypeptide comprising 80% or more sequence homology with the base sequence of the SEQ ID NO: 2, (d) DNA comprising base pair sequence capable of hybridizing under stringent conditions with base pair sequence complementary to the base pair sequence of the SEQ ID NO: 2, (e) DNA comprising base pair sequence in which one or more bases are substituted, deleted, inserted, added and/or inverted in the SEQ ID NO: 2, and (f) DNA encoding the polypeptide in which one ore more amino acid sequences are substituted, deleted, inserted, added or inverted in the amino acid sequence of the (SEQ ID NO: 1);    (2) vector comprising the DNA;    (3) transformant comprising the vector;    (4) method for preparing the diaphorase; and    (5) product comprising the diaphorase.    Sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication.