beta-Galactosidase and its significance in ripening of "Saijyo" Japanese Persimmon fruit.
The fruit extracts of ripening cv. Japanese Persimmon, "Saijyo", contained a number of glycosidases and glycanases. Among them, beta-galactosidase appeared to be the most significant, and the activity increased in parallel with tissue ripening. Persimmon beta-galactosidase was presented in at least three isoforms, beta-galactosidase-I (pI = 4.88), beta-galactosidase-II (pI = 6.76), and beta-galactosidase-III (pI = 7.05). beta-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 beta-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. beta-Galactosidase, in particular, seemed to play a major role in ripening the fruit.
Nakamura
Akihiro
A
Tsukuba R&D Center, Fuji Oil Co., Ltd., 4-3 Kinunodai, Yawara, Tsukuba-gun, Ibaraki 300-2497, Japan. 940080@so.fujioil.co.jp
Maeda
Hirokazu
H
Mizuno
Misae
M
Koshi
Yoko
Y
Nagamatsu
Yasunori
Y
D002241:Carbohydrates / Q000737:chemistry; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D029788:Diospyros / Q000201:enzymology* / Q000254:growth & development*; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008970:Molecular Weight; D010936:Plant Extracts / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry / Q000302:isolation & purification; D001616:beta-Galactosidase / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*
D002241:Carbohydrates; D007202:Indicators and Reagents; D010936:Plant Extracts; D010940:Plant Proteins; D011134:Polysaccharides; D006026:Glycoside Hydrolases; C020668:glycanase; D001616:beta-Galactosidase