PARTIAL-PURIFICATION AND CHARACTERIZATION OF THE CELL-WALL-ASSOCIATEDLANATOSIDE 15'-O-ACETYLESTERASE FROM DIGITALIS-LANATA SUSPENSION-CULTURES

The cell-wall-associated lanatoside 15'-O-acetylesterase (EC 3.1.1.6) from suspension-cultured Digitalis lanata Ehrh. (Scrophulariaceae) cel ls was partially purified by cell wall preparation, Mono S ion exchang e chromatography and gel filtration on Superose 12. The apparent molec ular mass of the enzyme was about 120 kDa as determined by gel filtrat ion. The enzyme has its pi at pH 8.7 and its pH-optimum at around 5.5. The apparent K-m-values for lanatoside A, lanatoside C and alpha-acet yldigoxin were 0.4 mM, 0.6 mM and 0.6 mM, respectively. The enzyme cou ld not be inhibited by p-hydroxymercuribenzoate or eserine and is boun d ionically to the cell wall.