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α-Galactosidase from Lens esculanta (red lentils) was purified 4090-fold through a multistep process involving acidification, ammonium sulphate fractionation, Sephadex gel filtration, DEAEcellulose and CM-cellulose chromatography. The purified enzyme is stable at 4°C for nearly six months with only a small loss of activity. It showed a pH optimum of 5.5 with raffinose as the substrate and 6.0 with p-nitrophenyl-α-D-galactoside. The Km for the former substrate was 40 mM and for the latter, 0.26 mM. The enzyme failed to liberate galactose from guar gum, tara gum and locust bean gum galactomannans. A study of the hydrolyzability of α-D-galactoside, α-D-fucoside and β-L-arabinoside showed that the presence of primary alcoholic group in the sugar was important for faster hydrolysis and a stronger binding. The substrate specificity studies indicated the absence of any related glycosidase activity in the α-galactosidase preparation. [ABSTRACT FROM AUTHOR]