Beta-hexosaminidase,an enzyme from ripening bell capsicum (Capsicum annuum var variata) |
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Authors: | Jagadeesh B H Prabha T N |
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Affiliation: | Biochemistry and Nutrition Department, Central Food Technological Research Institute, Mysore 570013, India. bhjagadeesh@yahoo.com |
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Abstract: | beta-Hexosaminidase activity increased significantly during fruit development and ripening of bell capsicum (Capsicuum annuum var. variata). Three isoforms of beta-hexosaminidase from bell capsicum could be resolved upon ion exchange chromatography with step wise gradient (0.10, 0.15 and 0.20 M NaCl) having an abundance of 38, 47 and 15% for isoforms I, II and III respectively. Isoforms I and II were further purified on gel permeation chromatography. The pH optimum for these two isoforms was around 5. Isoform II exhibited higher thermal stability. Hg(2+) and Zn(2+) inhibited both, but isoform I showed a much higher inhibition by Cu(2+) also. The K(m) for isoforms I and II with pnp-beta-D-N-acetyl glucosamine pyranoside was 3.00 and 1.75 mM, respectively. Isoform II on SDS-PAGE was found to be a monomer with a relative molecular mass of 85 kD. This isoform (the most major) appeared to be electrophoretically homogeneous. beta-Hexosaminidase is novel in the context of fruit ripening. This enzyme has not been reported from fruits and studied hitherto. |
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Keywords: | Capsicum annum var. variata Solanaceae Bell capsicum β-Hexosaminidase |
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