ASPARTYL PROTEINASE FROM CUCUMBER (CUCUMIS-SATIVUS) SEEDS - PREPARATION AND CHARACTERISTICS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 30  (1) , 23-31
Abstract
Aspartyl proteinase (EC 3.4.23.-) from cucumber seeds was purified by (NH4)2SO4 fractionation, chromatography on immobilized pepstatin and gel filtration on Sephacryl S-200. The preparation obtained was homogeneous on polyacrylamide-gel electrophoresis in acidic and alkaline media, and had a MW of 42,000 pI [isoelectric point] of 5.2, and showed the highest activity with denatured hemoglobin at pH 3.2. The proteinase was stable in slightly alkaline medium, but was inactivated in acidic medium, especially in the presence of NaCl. The enzyme activity was affected neither by the inhibitors of serine proteinases, sulfhydryl proteinases and metalloproteinases, nor by divalent metal ions. The enzyme was inactivated by inhibitors of aspartyl proteinases: 1,2,3-epoxy(p-nitrophenoxy)propane, diazoacetyl-DL-norleucine and pepstatin.

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