The purpose of this work was to extract peroxidase from Copaifera langsdorffii leaves (COP), measure its activity, compare it to that of Horseradish peroxidase and determine the optimum pH, the best extraction solution and the effect of additives on the COP activity. The results showed that COP has 81.6% of the activity of HRP and an optimum pH range between 5.5-6.0. The best extraction solution was a sodium phosphate buffer 50 mM, pH 6.0 and the best additive was PVPP. In conclusion, COP presents higher activity than peroxidases from different sources reported in the literature.264735739ADAMS, J.B., Regeneration and the kinetics of peroxidase inactivation (1997) Food Chemistry, 60 (2), pp. 201-206_ Review: Enzyme inactivation during heat processing of food-stuffs. International Journal of Food Science and Technology, v. 26, n. 1, p. 1-20, 1991ALLAIN, C.C., POON, L.S., CHAN, C.S.G., RICHMOND, W.R., FU, P.C., Enzymatic determination of total serum cholesterol (1974) Clinical Chemistry, 20 (4), pp. 470-475ANGUITA, G., MARTÍN, R., GARCÍA, T., MORALES, P., HAZA, A.I., GONZÁLEZ, I., SANZ, B., HERNÁNDEZ, P.E., A competitive enzyme-linked immunosorbent assay for detection of bovine milk in ovine and caprine milk and cheese using a monoclonal antibody against bovine-casein (1997) Journal of Food Protection, 60 (1), pp. 64-66ARNAO, M.B., CANO, A., HERNÁNDEZ-RUIZ, J., GARCÍA- CÁNOVAS, F., ACOSTA, M., Inhibition by L-ascorbic acid and other antioxidants of the 2-2′-azidobis (3-ethylbenzothiazoline-6-sulfonic acid) oxidation catalyzed by peroxidase: A new approach for determining total antioxidant status of foods (1996) Analytical Biochemistry, 236 (2), pp. 255-261BAUCHER, M., CHRISTENSEN, J.H., MEYERMANS, H., CHEN, C., VAN DOORSSELAERE, J., LEPLÉ, J.C., PILATE, G., BOERJAN, W., Applications of molecular genetics for biosynthesis of novel lignins (1998) Polymer Degradation and Stability, 59 (1-3), pp. 47-52CALDERÓN, A.A., ZAPATA, J.M., MUÑOZ, R., ROS BACELÓ, A., Localization of peroxidase in grapes using nitro-cellulose blotting of freezing/thawing fruits (1993) HortScience, 28 (1), pp. 38-40CASELLA, L.GULLOTTI, M.NARCHESINI, A.PETRARULO, M. Rapid enzymatic method for vitamin C assay in fruits and vegetables using peroxidase. Journal of Food Science, v. 54, n. 2, p. 374-375, 378, 1989CHANG, T., HUANG, S.H., An enzyme-linked immunosorbent assay for the rapid detection of Staphylococcus aureus in processed foods (1994) Journal of Food Protection, 57 (2), pp. 184-189CHEN, C.H., CHANG, T.C., An enzyme-linked immunosorbent assay for the rapid detection of Vibrio parahaemolyticus (1995) Journal of Food Protection, 58 (8), pp. 873-878CHU, F.S., FAN, T.S.L., Indirect enzyme-linked immunsorbent assay for saxitoxin in shellfish (1985) Journal of AOAC International, 68 (1), pp. 13-16FATIBELLO-FILHO, O., VIEIRA, I.C., L-ascorbic acid determination in pharmaceutical formulations using a biosensor based on carbon paste modified with crude extract of Zucchini (Cucurbita pepo) (2000) Journal Brazilian Chemical Society, 11 (4), pp. 412-418GAZARYAN, I.G., LAGRIMINI, L.M., Purification and unusual kinetic properties of a tobacco anionic peroxidase (1996) Phytochemistry, 41 (4), pp. 1029-1034GLAZE, W.H., Reaction products of ozone: A review (1987) Environmental Science and Technology, 21 (3), pp. 224-227HAMMERSCHMIDT, R., NUCKLES, E., KERE, J., Association of enhanced peroxidase activity in induced systemic resistance of cucumber to Colettotrichum lagenarium (1982) Physiology Plant Pathology, 20 (1), pp. 73-82HOLSCHUH, H. J. Isolamento, purificação e caracterização bioquímica de peroxidase da carambola (Averrhoa carambola, L.). Campinas, 2000, 159p. Tese (Doutor em Ciência de Alimentos) - Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas (UNICAMP)HOUGHTON, P.J., ZARKA, R., HERAS, B., HOULT, J.R., Fixed oil of Nigella sativa and derived thymoquinone inhibit eicosanoid generation in leukocytes and membrane lipid peroxidation (1995) Planta Medica, 61 (1), pp. 33-36IARC, Monographs on the evaluation of the carcinogenic risk of chemicals to humans. Allyl compounds, aldehydes, epoxides and peroxides, IARC, Lyon, France v. 36, p. 267, 1985ITO, Y., TONOGAI, Y., SUZUKI, H., Improved 4-aminoantipyrine colorimetry for detection of residual hydrogen-peroxide in noodles, fish paste, dried fish and herring roe (1981) Journal of AOAC International, 64 (5), pp. 1448-1452JACKSON, P.RICARDO, C. P. P. Cytochrome C aided resolution of Lupinus albus isoperoxidases in a cathodal polyacrylamide gel electrophoresis system. Analitical Biochemistry, v. 200, n. 1, p. 36-41, 1992JOHANSSON, E., MARKO-VARGA, G., GORTON, L., Study of a reagent- and mediator-less biosensor for D-amino acids based on co-immobilized D-amino acid oxidase and peroxidase in carbon paste electrodes (1993) Journal of Biomaterials Applications, 8 (2), pp. 146-173KHAN, A.A., ROBINSON, D.S., Hydrogen donor specificity of mango isoperoxidases (1994) Food Chemistry, 49 (4), pp. 407-410KOK, G.M., HOLLER, T.P., LOPEZ, M.B., Chemiluminescent method for determination of hydrogen-peroxide in ambient atmosphere (1978) Environmental Science and Technology, 12 (9), pp. 1072-1076KOKÇAM, I., NAZIROGLU, M., Antioxidants and lipid peroxidation status in the blood of patients with psoriasis (1999) Clinica Chimica Acta, 289 (1-2), pp. 23-31LIAO, X.-R., ZHU, X.-C., HE, P.-C., A cationic peroxidase from leaves of Vitis pseudoreticulata (1999) Phytochemistry, 51 (1), pp. 143-145LIN, Z.-F., CHEN, L.-H., ZHANG, W.-Q., Peroxidase from Ipomoea cairica (L) SW. Isolation, purification and some properties (1996) Process Biochemistry, 31 (5), pp. 443-448LÓPEZ-SERRANO, M., ROS BARCELÓ, A., Purification and characterization of a basic peroxidase isoenzyme from strawberries (1996) Food Chemistry, 55 (2), pp. 133-137McCLEAR, B.V., GLENNIE-HOLMES, M., Enzymatic quantification of (1-3) (1-4)-β-D-Glucan in barley and malt (1985) Journal of the Institut of Brewing, 91 (2), pp. 285-295NAKAYAMA, T., AMACHI, T., Fungal peroxidase: Its structure, function, and application (1999) Journal of Molecular Catalysis B: Enzymatic, 6 (3), pp. 185-198RAMAMURTHY, M.S., USSUF, K.K., NAIR, P.M., THOMAS, P., Lignin biosynthesis during wound healing of potato tubers in response to gamma irradiation (2000) Postharvest Biology and Technology, 18 (3), pp. 267-272ROS BARCELÓ, A., MUÑOZ, R., SABATER, F., Lupin peroxidase. I. Isolation and characterization of cell wallbound isoperoxidase activity (1987) Physiology Plantarum, 71 (4), pp. 448-454ROS BARCELÓ, A.ZAPATA, J. M.CALDERÓN, A. A. Tissue-specific expression of peroxidase activity in seedless grapes (Vitis vinifera cv. Thompson and Flame). Revista Espanola de Ciencia y Tecnologia de Alimentos, v. 34, n. 2, p. 110-116, 1994aSELLERS, R.M., Spectrophotometric determination of hydrogen-peroxide using potassium titanium (IV) oxalate (1980) Analyst, 105 (1255), pp. 950-954SERGEYEVA, T.A., LAVRIK, N.V., RACHKOV, A.E., KAZANTSEVA, Z.I., PILETSKY, S.A., EL'SKAYA, A.V., Hydrogen peroxide - sensitive enzyme sensor based on pthalocyanine thin film (1999) Analytica Chimica Acta, 391 (3), pp. 289-297SOARES, C.M.F., SANTANA, M.H.A., ZANIN, G.M., CASTRO, H.F., Effect of poly (ethylene) glycol and albumin on the immobilization of microbial lipase and catalysis and catalysis in organic media (2003) Química Nova, 26 (6), pp. 832-838SRIVASTAVA, O.P., VAN HUYSTEE, R.B., An inter-relationship among peroxidase, IAA oxidase and polyphenoloxidase from plant cells (1977) Canadian Journal of Botany, 55 (12), pp. 2630-2636