title: Beta-hexosaminidase, an enzyme from ripening bell capsicum (Capsicum annuum var variata).
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.
mesh_terms: D002212:Capsicum / Q000201:enzymology* / Q000254:growth & development; D004795:Enzyme Stability; D005638:Fruit / Q000201:enzymology / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D020033:Protein Isoforms / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013696:Temperature; D001619:beta-N-Acetylhexosaminidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D001619:beta-N-Acetylhexosaminidases