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Our objective in this study was to extend our knowledge of β-galactosidase in an attempt to elucidate the role of β-galactosidase on ripening and softening of persimmon (Diospyros kaki cv. Fuyu) fruits. To accomplish this, we have partially purified and characterized the β-galactosidase from persimmon fruits and produced polyclonal antibodies specific for this enzyme. The Km and Vmax values of β-galactosidase were 1.92 × 10^(-3) mM and 4.20 × 10^(-2) mmole ρ-nitrophenyl-β-D-galactopyranoside/㎖/60 min., respectively. The β-galactosidase was stable pH between 2.0 and 6.0, and the optimum pH was at about 4.0. The β-galactosidase was stable below 40℃, and the temperature optimum was 50℃. The activity of this enzyme was inhibited greatly by Hg^(++), SDS, and EDTA. Polyclonal antibody to persimmon β-galactosidase was raised in New Zealand White rabbit against the gel-purified 44 kD β-galactosidase subunit. Immunoblot of β-galactosidase with crude and partially purified protein was conducted by western blot analysis, and an apparent 44 kD protein band was obtained.
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