A galactomannan-hydrolysing α-galactosidase from jack fruit (Artocarpus integrifolia) seed: Affinity chromatographic purification and properties.
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Date
1987-03
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Abstract
An acid α-galactosidase from the seeds of the jack fruit seed (Artocarpus
integrifolia) has been purified to homogeneity by affinity chromatography on a matrix
formed by cross-linking the soluble α-galactose-bearing guar seed galactomannan. The
35kDa enzyme was a homotetramer of 9·5kDa subunits. Its carbohydrate part (5·5%) was
composed of galactose and arabinose. The Km with p-nitrophenyl α-D-galactoside as substrate
was 0·35 mM. The Ki values indicated inhibition by galactose, 1-O-methyl α-galactose
and melibiose in the decreasing order. Among α-galactosides, the enzyme liberated
galactose from melibiose, but not from raffinose or stachyose at its pH optimum (5·2). The
guar seed galactomannan was however efficiently degalactosidated; limited enzyme
treatment abolished the precipitability of the polysaccharide by the α-galactose-specific jack
fruit seed lectin, and complete hydrolysis yielded insoluble polysaccharide. Though similar
in sugar specificity and subunit assembly, α-galactosidase and the lectin coexisting in the
jack fruit seed gave no indication of immunological identity.
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Keywords
α-Galactosidase, galactomannan, jack fruit seed, Artocarpus integrifolia
Citation
Appukuttan P S, Basu Debkumar. A galactomannan-hydrolysing α-galactosidase from jack fruit (Artocarpus integrifolia) seed: Affinity chromatographic purification and properties. Journal of Biosciences. 1987 Mar; 12(1): 61-69.