ALPHA-L-ARABINOFURANOSIDASE FROM CELL-WALLS OF JAPANESE PEAR FRUITS

Cell wall-bound glycosidase activities were measured in pre-ripe and r ipe fruits of Japanese pears (Pyrus serotina Rehd. var. culta. cv. Hos ui). alpha-L-Arabinofuranosidase (EC. 3.2.1.55) activity increased dra matical ly with fruit ripening and its activity was assayed during fru it development and ripening. After the fruit enlargement stage, cell w all-bound alpha-L-arabinofuranosidase activity increased 15-fold with fruit ripening. The enzyme was solubilized from cell walls using the c helator trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid and th e solubilized enzyme purified using DEAF-cellulose, hydroxyapatite, Mo no Q and Sephadex G-100 chromatography. The purified enzyme was a M(r) 42 000 monomer on SDS-PAGE. Optimum pH activity was 5.0 and the K-m v alue was 34 mM for p-nitrophenyl-alpha-L-arabinofuranoside.