[An optimal method of determining the level of cathepsin A in blood platelet homogenates]

Blood platelet cathepsin A hydrolyzes Cbz-Glu-Tyr most intensively at pH 5.0, it does so too, with Cbz-Glu-Phe, but to a smaller extent. Using the ninhydrin method for estimation of the released tyrosine++ or phenylalanine previous elimination of amino acids++ and low-molecular peptides is necessary as it is too including alpha-amine nitrogen released by platelet proteases from peptides and proteins.