Abstract
The fruit extracts of ripening cv. Japanese Persimmon, “Saijyo”, contained a number of glycosidases and glycanases. Among them, β-galactosidase appeared to be the most significant, and the activity increased in parallel with tissue ripening. Persimmon β-galactosidase was presented in at least three isoforms, β-galactosidase-I (pI=4.88), β-galactosidase-II (pI=6.76), and β-galactosidase-III (pI=7.05). β-Galactosidase-III had exo-type galactanase activity, while the others did not.
The activity of endo-type glycanases was a maximum in immature green or yellow fruits. The firmness of the pulp tissue decreased dramatically, and the amount of water-soluble polysaccharide (WSS) increased. The enzyme activities of exo-type glycosidases, especially β-galactosidase, appeared maximal in mature red fruits. The amount of extractable pectin remained unchanged, although the galactose content of the high-molecular-weight fraction in WSS decreased dramatically.
These results suggest that the ripening of persimmon was caused by the solubilization of pectic polysaccharide by endo-type glycanases and digestion by exo-type glycosidases. β-Galactosidase, in particular, seemed to play a major role in ripening the fruit.
