Glycosidases of apple fruit: A multi‐functional β‐galactosidase

Abstract

Extraction of Spartan apple (Malus domestica) fruit acetone powder and fractionation of the extract on DEAE‐agarose allowed detection and quantification of 10 glycosidases active toward 4‐methylumbelliferyl glycosides. Hydrolysis was measured fluorimetrically. The predominant activity, a β‐d‐galactosidase (EC 3.2.1.23), labile upon purification, was stabilized by soluble PVP. Molecular weights, measured by gel permeation HPLC, pH optima and Km values were obtained for most glycosidase activities. Multiple forms of several activities were found. The major α‐d‐ and β‐d‐galactosidases were resolved on phosphocellulose. The β‐d‐galactosidase so obtained had associated α‐l‐arabinopyranosidase and β‐d‐fucosidase activities which were retained upon GP‐HPLC. Mixed substrate kinetic analysis and inhibition analysis of this fraction indicated that the enzyme has 3 catalytic sites, 1 for each substrate, whose substrates mutually influence each other's activity positively.

Four glycoside hydrolases are differentially modulated by auxins, cytokinins, abscisic acid and gibberellic acid in apple fruit callus cultures

“…Each value represents the mean ± SE of three replicates enzyme family whose members are responsive to different endogenous controls during growth and ripening. a-Araf activity increases in ripening apples (Dick et al 1990;Goulao et al 2007;Yoshioka et al 1995) while arabinose content decreases during the overripening stage (Peña and Carpita 2004). Nevertheless, a-Araf is present not only during fruit ripening but also during the early stages of fruit development, both in apple (Goulao et al 2007) and in Japanese pear, another pome fruit (Tateishi et al 1996).…”

Multiple forms of β‐galactosidase from mango (Mangifera indica L Alphonso) fruit pulp

“…12 Some of the properties of β-galactosidase from mango fruit cv Alphonso, noted from this study, are comparable with those of cv Hurumanis, 5 and other fruits as well. The pH optimum for β-galactosidase isoforms is similar to those of apple, 15 coffee 18 and tomato, 7 while it is lower than that of sapota β-galactosidase. 19 The pH stability of mango β-galactosidase is similar to that of tomato β-galactosidase isoforms.…”

“…18 The M r values for the three isoforms of mango were similar to those of tomato isoforms 7 and differed from those of sapota 19 and apple. 15 The M r of isoform II is similar to β-galactosidase isoforms of sweet cherry, 20 kiwi fruit 14 and avocado. 16 Various other plant β-galactosidases in the M r range from 49 to 300 kDa have been reported.…”

“…17 β-Galactosidase acting on galactans was reported in fruits such as apple. 15 The kiwi β-galactosidase was 10 times Note: β-galactosidase activity in control is taken as 100. The results shown are means of triplicate determinations, SEM ± 0.08. more active towards kiwi galactan and 20 times more active towards apple galactan than the apple β-galactosidase.…”

“…The results shown are means of triplicate determinations, SEM ± 0.08. more active towards kiwi galactan and 20 times more active towards apple galactan than the apple β-galactosidase. 15 Hemicelluloses were found to be degraded by β-galactosidase from mung bean seedlings. 12 Some of the properties of β-galactosidase from mango fruit cv Alphonso, noted from this study, are comparable with those of cv Hurumanis, 5 and other fruits as well.…”