Author(s): Priolo N, Morcelle del Valle S, Arribre MC, Lpez L, Caffini N, Priolo N, Morcelle del Valle S, Arribre MC, Lpez L, Caffini N
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Abstract A new protease (araujiain h I) was purified to mass spectroscopy homogeneity from the latex of Araujia hortorum Fourn. (Asclepiadaceae) fruits by ultracentrifugation and ion exchange chromatography. The enzyme has a molecular mass of 24,031 (mass spectrometry) and an iso-electric point higher than 9.3. The optimum pH range for casein hydrolysis was 8.0-9.5. The enzyme showed remarkable caseinolytic activity at high temperatures, although its thermal stability decayed rapidly. The proteinase was activated by thiol compounds and inhibited by common thiol-blocking reagents, particularly E-64 and HgCl2, suggesting the enzyme belongs to the cysteine protease family. The concentration of active sites as determined by titration with E-64 was 3.3 microM. When assayed on N-alpha-CBZ-amino acid-p-nitrophenyl esters, the enzyme showed higher preference for the glutamine derivative, followed by those of alanine, asparagine, glycine, and leucine, in decreasing order. Partial homology (36-48\%) with other plant cysteine proteinases was observed in an internal fragment obtained by Protease V8 treatment.
This article was published in J Protein Chem
and referenced in Journal of Bioprocessing & Biotechniques