The presence of endo- and exoproteolytic activity in peroxisomes was d
etected in cell organelles purified from pea leaves. By PAGE using dif
ferent exopeptidase substrates (L-aa-betaNA), one leucine aminopeptida
se (AP) was found in peroxisomes. The peroxisomal AP was characterized
as a serine protease and had a maximal activity at pH 7.5, a molecula
r mass of 56.8 kDa and a pI of 5.3. This enzyme was mainly present in
the soluble fraction of peroxisomes. The occurrence of proteases in pe
roxisomes suggests that they might be involved in the protein turnover
and processing of imported precursor polypeptides in peroxisomes.