Philibertain g I, the Most Basic Cysteine EndopeptidasePurified from the Latex of Philibertia gilliesii Hook. et Arn. (Apocynaceae) |
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Authors: | C. Sequeiros M. J. Torres S. A. Trejo J. L. Esteves C. L. Natalucci L. M. I. López |
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Affiliation: | (1) CENPAT-CONICET Centro Nacional Patagónico, Blvd. Brown s/n, 9120 Puerto Madryn, Chubut, Argentina;(2) LIPROVE, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 711, 1900 La Plata, Argentina |
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Abstract: | A new papain-like cysteine peptidase isolated from latex of Philibertia gilliesii Hook. et Arn., Apocynaceae (formerly Asclepiadaceae) has been purified and characterized. The enzyme, named philibertain g I, is the most basic component present in latex extracts and was purified by acetone fractionation followed by cation exchange chromatography (SP-Sepharose HR) using FPLC system. Homogeneity was confirmed by SDS-PAGE and mass spectroscopy (MS). Molecular mass of the enzyme was 23,530 Da (MALDI-TOF MS), its isoelectric point was >10.25, and maximum proteolytic activity (casein) was achieved at pH 7–8. The new protease was inhibited by E-64 a cysteine peptidases inhibitor. Km was 0.15 mM, using PFLNA as substrate. The N-terminal sequence of philibertain g I (LPASVDWRKEGAVLPIRHQGQCG) was compared with those of twenty plant proteases. Philibertain g I showed the higher degree of identity (73%) with caricain, one of the Carica papaya endopepetidases. |
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Keywords: | Asclepiadeae cysteine endopeptidase Philibertia gilliesii plant latex plant protease |
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