Purification and Characterization of Cynomolgus Monkey Tryptase

Cynomolgus monkey tryptase was purified to homogeneity from lung tissue. Reducing SDS-PAGE analysis of the monkey enzyme produced a doublet at 30–32 kDa, which reacted with antibodies against human lung tryptase on a Western blot. N-terminal sequence analysis of the monkey enzyme yielded a sequence that was identical to human tryptase out to 15 residues. Gel filtration chromatography either in the presence or absence of heparin indicated that the monkey enzyme had a molecular mass of approximately 250 kDa and 140 kDa, respectively, consistent with the formation of a tetramer that can bind heparin. Other similarities between human and monkey tryptase included the ability to degrade vasoactive intestinal peptide and a resistance to inhibition by biological serine protease inhibitors. However, the two enzymes displayed markedly different pH stability profiles. Monkey tryptase was unstable at pH values over 7.0, even in the presence of heparin, displaying a half-life of 10.9 min at pH 8.0. In addition, the stabilizing effect of heparin was pH dependent, being most prevalent at lower pH values. Therefore, the biological activity of monkey tryptase may be controlled by both pH and the availability of heparin.