Cathepsin L-like protease from Xenopus embryos that is stimulated by nucleoside phosphates and nucleic acids

An acid thiol protease that was activated at an early stage of embryogenesis was purified from Xenopus embryos. The N-terminal amino acid sequence (16 residues) of the heavy chain of the enzyme was similar to that of cathepsin L. The proteolytic activity of the protease was enhanced by ATP. Other nucleoside triphosphates, AMP and nucleic acids also enhanced the proteolytic activity. The possible mechanism and biological significance of the activation of the protease in Xenopus embryos are discussed.