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Asian Journal of Biochemistry

Year: 2007 | Volume: 2 | Issue: 6 | Page No.: 415-420
Research Article

Possible Functional Roles of Exposed Sulfhydryl Groups in Malted and Unmalted African Finger Millet Seed (Eluesine coracana) β-amylase

Ayodele O. Kolawole
Department of Biochemistry, Federal University of Technology, Akure, Nigeria
LiveDNA: 234.5472
Joshua O. Ajele
Department of Biochemistry, Federal University of Technology, Akure, Nigeria
The behavior of exposed sulfhydryl groups of β-amylase from malted and unmalted African finger millet seed was investigated for their possible functional roles by chemical modification studies using 5,5’-dithiobis-(2-nitro-benzoic acid) (DTNB). The malted and unmalted enzyme purified by α-cyclodextrin Sepharose 6B affinity column chromatography was inhibited by the sulfhydryl reagent. The chemical modification study revealed that there were three sulfhydryl and four sulfhydryl groups in β-amylase from both unmalted and malted seed, respectively each having one exposed sulfhydryl group; performing different roles and were essential for catalytic activity. The result shows a distinction between the in situ β-amylase from unmalted seed and de novo β-amylase in malted seed synthesized during malting. The malted seed β-amylase was oxidatively dimerized by subjecting it to 0.3 M potassium ferricyanide in 3.0 M urea. The dimerized enzyme was inactive. The result from the DTNB chemical modification study of the exposed sulfhydryl group in the β-amylase purified from malted African finger millet seed before oxidation of the group shows that the sulfhydryl group is involved in the formation of dimers.
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