Enzyme electrode composed of the pyruvate oxidase from Pediococcus species coupled to an oxygen electrode for measurements of pyruvate in biological media.

Pyruvate oxidase from Pediococcus species was immobilized with gelatin and insolubilized in film form by tanning with glutaraldehyde. The film was fixed onto the tip of an oxygen electrode. The enzyme electrode was specific for pyruvate measurements. This electrode was sensitive to 0.1 mM and could be used up to a final pyruvate concentration of 2 mM. At each step of the enzymatic film preparation and assay 0.7 mM thiamine pyrophosphate, 10 microM flavin adenine dinucleotide, 5 mM Mg2+ and 10 mM phosphate buffer were necessary. A computerized probe allowed successive measurements every 3 min for more than 20 h with the same enzymatic film. The reproducibility for the same pyruvate concentration was 2% during 400 assays without special optimization. This enzyme electrode has many applications in basic (metabolism, enzymology) and applied (blood, yoghurt) research. Results obtained from assays carried out in yoghurt are presented.