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. 1989 Dec;91(4):1414–1418. doi: 10.1104/pp.91.4.1414

Proteolytic Activity at Alkaline pH in Oat Leaves, Isolation of an Aminopeptidase 1

Leonardo M Casano 1, Marcelo Desimone 1, Victorio S Trippi 1
PMCID: PMC1062199  PMID: 16667194

Abstract

Proteolytic activity in oat leaf extracts was measured with both azocasein and ribulose bisphosphate carboxylase (Rubisco) as substrates over a wide range of pH (3.0-9.2). With either azocasein or Rubisco activity peaks appeared at pH 4.8, 6.6, and 8.4. An aminopeptidase (AP) which hydrolyzes leucine-nitroanilide was partially purified. Purification consisted of a series of six steps which included ammonium sulfate precipitation, gel filtration, and two ionic exchange chromatographies. The enzyme was purified more than 100-fold. The apparent Km for leucine-nitroanilide is 0.08 millimolar at its pH optimum of 8.4. AP may be a cystein protease since it is inhibited by heavy metals and activated by 2-mercaptoethanol. Isolated chloroplasts were also able to hydrolyze leucine-nitroanilide at a pH optimum of 8.4, indicating that AP could be localized inside the photosynthetic organelles.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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