Proteolytic activity and the cysteine protease profile were determined for enzymatic extracts (EE) from Carica papaya L cv. Maradol harvest by-products (stems, unripe fruit, petioles and leaves). The proportion of each by-product type in the sampled plantation was calculated. Polypeptide bands were identified by SDS-PAGE for each EE and molecular weight calculated for the cysteine proteases. Leaf and fruit tissue had the highest protein contents of the by-products. Leaf tissue also produced the highest total EE yield. All the SDS-PAGE gels for the EE's exhibited an approximately 23 kDa band probably corresponding to papain. The zymography profiles of the EE's were similar, with bands at approximately >202.8, 76.8, 55.4 and 46.5 kDa. The fruit EE had the highest specific proteolytic activity and the leaf EE the lowest. Fruit and stem by-products are the most promising for proteolytic enzyme extraction. (C) 2008 Elsevier Ltd. All rights reserved.