Polysaccharide hydrolases from leaves of Boscia senegalensis: properties of endo-(1-->3)-beta-D-glucanase |
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Authors: | Dicko M H Searle-van Leeuwen M J Traore A S Hilhorst R Beldman G |
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Institution: | (1) Laboratories of Biochemistry and Food Chemistry, Department of Agrotechnology and Food Sciences, Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands;(2) Laboratoire de Biochimie, CRSBAN, UFR-SVT, Université de Ouagadougou, 03 B. P. 7021, Ouagadougou 03, Burkina-Faso |
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Abstract: | The leaves of Boscia senegalensis are traditionally used in West Africa in cereal protection against pathogens, pharmacologic applications, and food processing.
Activities of α-amylase, β-amylase, exo-(1→3, 1→4)-β-d-glucanase, and endo-(1→3)-β-d-glucanase were detected in these leaves. The endo-(1→3)-β-d-glucanase (EC3.2.1.39) was purified 203-fold with 57% yield. The purified enzyme is a nonglycosylated monomeric protein with
a molecular mass of 36 kDa and pI≥10.3. Its optimal activity occurred at pH 4.5 and 50°C. Kinetic analysis gave V
max, k
cat
, and K
m
values of 659 U/mg, 395 s−1, and 0.42 mg/mL, respectively, for laminarin as substrate. The use of matrix-assisted laser desorption ionization time-of-flight
mass spectrometry and high-performance liquid chromatography revealed that the enzyme hydrolyzes not only soluble but also
insoluble (1→3)-β-glucan chains in an endo fashion. This property is unusual for endo-acting (1→3)-β-d-glucanase from plants. The involvement of the enzyme in plant defense against pathogenic microorganisms such as fungi is
discussed. |
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Keywords: | α -Amylase β -amylase β -glucanase disodium 2 2′ -bichinconitate yeast glucan high-performance liquid chromatography matrix-assisted laser desorption/ionization time-of-flight mass spectrometry |
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