The present study, describes a methodology of dosage of the glycerol 3-phosphate oxidase (GPO; EC 1.1.3.21) from baker's yeast. The glycerol-3-phosphate oxidase  is an oxido-reductase found, mainly, in lactic acid bacteria and inexistent in the human organism. It is a flavoprotein responsible for the catalysis of the oxidation reaction  of glycerol 3-phosphate into dihydroxyacetone phosphate, using oxygen as aceptor of electrons to produce hydrogen peroxide. The crude cellular extract of dry baker's yeast from Mauri Brasil Ind. Imp. Ltda, was prepared as described by Tininis, Master's degree dissertation, UNESP: 124, 2001. The standardization of the activity of the glycerol-3-phosphate oxidase was accomplished as described by Suchova et al, Enzyme Microbiol. Technol., 14: 917, 1992. The following reaction mixture was used: glycerol-3-phosphate in solution 0.1 M Tris-HCl buffer at pH 8.0 containing 0.1% Triton X-100, 4-aminoantipyrine, phenol, horseradish peroxidase and the preparation of enzyme diluted to start the reaction. The mixture was incubated at 60°C for 2 hours and the reaction was stopped by adding the solution SDS. The protein concentration was determined according to the method of Folin-Lowry modified by Layne, Methods Enzymology 3: 447,1957, using bovine serum albumin as standard protein. This method doses glycerol-3-phosphate, an important intermediate metabolite, with low cost and in the range of 23.0 x 10^-3 – 20.7 x 10^-2 g/L. Coupled to other reactions, this enzyme category is of potential interests for a variety of chemical processes, as those used in the pharmaceutical and nutritious industry, especially, in the glycerol determination, a product thoroughly found in the nature as constituent of lipids and present in beverages (wines) and industrialized products.

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