Funastrain c II: A Cysteine Endopeptidase Purified from the Latex of <i>Funastrum clausum</i>

• Autores: Morcelle del Valle, Susana Raquel; Trejo, Sebastián Alejandro; Canals, Francesc; Avilés, Francesc X.; Priolo de Lufrano, Nora Silvia
• Año de publicación: 2004
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Biología; Cysteine endopeptidases; <i>Funastrum clausum</i>; Latex; Plant proteases; Protein purification
• Institución: Universidad Nacional de La Plata

A cysteine endopeptidase, named funastrain c II, was isolated and characterized from the latex of Funastrum clausum (Asclepiadaceae). The molecular mass (mass spectrometry) of the protease was 23.636 kDa. The analysis of funastrain c II by SDS-PAGE revealed a single polypeptide chain. The enzyme showed a remarkable stability of its caseinolytic activity after incubation at temperatures as high as 70°C. Inhibition and activation assays indicated the cysteinic nature of the funastrain c II catalytic site. The optimum pH of funastrain c II enzymatic activity varied according to the substrate used (9.0–10.0 for casein and 6.2–6.8 for PFLNA). Kinetic parameters were determined for N-α-CBZ-Ala p-nitrophenyl ester (Km = 0.0243 mM, kcat = 1.5 s–1) and L-pyroglutamyl-L-phenylalanyl-L-leucine-p-nitroanilide (PFLNA; KM = 0.1011 mM, kcat = 0.9 s–1). The N-terminal sequence of funastrain c II showed considerable similarity to other proteases isolated from latex of different Asclepiadaceae species as well as to other cysteine proteinases belonging to the papain family.
Centro de Investigación de Proteínas Vegetales