Identification of cathepsin L-like proteinase and aminopeptidase in yolk granules of the sand worm,Nereis diversicolor

• 1.1. Two proteinases have been identified in yolk granules of Nereis diversicolor mature oocytes, an aminopeptidase and an acid cysteine proteinase.
• 2.2. The aminopeptidase was identified as a metallo-enzyme having a molecular weight of about 260 kDa.
• 3.3. Except that the acid cysteine proteinase is a high molecular weight protein (200 kDa) and has a very low pH optimum (3.0), the enzyme possesses properties resembling those of mammalian cathepsin L.
• 4.4. The cathepsin L-like proteinase was found to be liable to the in vitro proteolysis of the yolk granule proteins and is therefore suggested to be involved in yolk protein processing.