Comparison of asclepiadaceae latex proteases and characterization of Morrenia brachystephana Griseb. cysteine peptidases

Partial characterization of the crude proteolytic extracts of five Asclepia daceae species namely Araujia hortorum Fourn,, Asclepias curassavica L., Fu nastrum clausum (Jacq,) Schlechter, Morrenia brachystephana Griseb, and Mor renia odorata (Hook et Am.) Lindley, and a comparison of these results and those from other Asclepiadaceae species are reported. Additionally, the cru de extract from M. brachystephana was submitted to further purification and characterization. The crude enzyme showed high proteolytic activity when a ssayed on casein in the presence of 12 mM cysteine but was strongly inhibit ed by very low concentrations of sodium iodoacetate (0.01 mM) and mercuric chloride (0.1 mM) suggesting that the enzyme belongs to the cysteinyl-prote ases type, Fractioned acetone precipitation followed by cation exchange chr omatography allowed the separation of two basic (pI > 9.3) proteolytically active fractions, both homogeneous by sodium dodecyl sulphate-polyacrylamid e gel electrophoresis and with similar molecular masses (25.5 and 26 kDa). (C) 1998 John Wiley & Sons, Ltd.