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Isolation and partial purification of beta-galactosidases from cotyledons of two cowpea cultivarsDOI: 10.1590/S0103-31312001000300001 Keywords: cotyledons, isozymes, vigna unguiculata, vita 3 and vita 5 cultivars, salt tolerance. Abstract: three isoforms of b-galactosidases were isolated and partially purified from the cotyledons of quiescent seeds of vita 3 and vita 5 cowpea [vigna unguiculata (l.) walp.] cultivars differing in water and salt stress tolerance. the purification procedure consisted of ammonium sulfate fractionation, acid precipitation, ion exchange chromatography through deae-sephadex and affinity chromatography through lactosyl-sepharose columns. the three isoforms isolated from the two cultivars showed the same chromatographic patterns, same optimum of temperature for enzyme activity assay (60oc), identical thermal stability up to 50°c, and similar ph optima (3-4). however, they differed from each other in sensitivity towards metal ions and certain chemical agents presents in the assay medium. the results have shown that the observed differences in b-galactosidases from the cotyledons of quiescent seeds were not sufficient to relate them to stress tolerance.
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