A preliminary survey demonstrated activity for α-D-glucosidase, α-D-mannosidase, α-L-arabinosidase, β-D-glucosidase, β-D-xylosidase, and β-D-galactosidase in orange fruit flavedo and albedo tissue, α-L-Rhamnosidase was not detected. Subsequently, a β-glucosidase was purified from mature fruit rag tissue (composed of intersegmental septa, squeezed juice sacs, and fruit core tissue) of Citrus sinensis var. Valencia. The β-glucosidase exhibited low levels of activity against p-nitrophenyl-β-D-fucopyranoside (13.5%) and p-nitrophenyl-a-D-glucopyranoside (7.0%), compared to its activity against p-nitrophenyl-β-D-glucopyranoside (pNPG, 100%). The enzyme was purified by a combination of ion exchange (anion and cation) and gel filtration (Superdex and Toyopearl HW-55S) chromatography. It has an apparent molecular mass of 64 kDa by denaturing electrophoresis or 55 kDa by gel filtration chromatography (BioGel P-100). Hydrolysis of pNPG demonstrated a pH optimum between 4.5 and 5.5. At pH 5.0 the temperature optimum was 40 °C. At pH 5.0 and 40 °C the K_m forpNPG was 0.1146 mM and it had a V_max of 5.2792 nkatal.mg^-1 protein (katal = 0.06 International Units = the amount of enzyme that produces, under standard conditions, one μmol of product per min). Of the substrates tested, the enzyme was most active against the disaccharide cellobiose (1⇒4), but was not active against p-nitrophenyl-β-D-cellobioside. High levels of activity also were observed with the disaccharides laminaribiose (1⇒3), gentiobiose (1⇒6), and sophorose (1⇒2). Activity greater than that observed with pNPG was obtained with the flavonoids hesperetin-7-glucoside and prunin (naringenin-7-glucoside), salicin, mandelonitrile-β-D-glucoside (a cyanogenic substrate), and sinigrin (a glucosinolate). The enzyme was not active against amygdalin, coniferin, or limonin glucoside.

EXPLOR_STEP=$WICRI_ROOT/Wicri/Bois/explor/OrangerV1/Data/Main/Exploration

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{{Explor lien
   |wiki=    Wicri/Bois
   |area=    OrangerV1
   |flux=    Main
   |étape=   Exploration
   |type=    RBID
   |clé=     Pascal:02-0002042
   |texte=   Purification and characterization of a beta-glucosidase from Citrus sinensis var. valencia fruit tissue
}}