Immunological studies on cathepsins B and H from rat liver

The immunological properties of thiol proteinases from rat liver, cathepsin B, H, and L, were examined. Rabbit antisera were prepared against cathepsins B and H from rat liver. Anti-cathepsin B and H ser quantitatively precipitated only the corresponding enzyme protein. On immunodiffusion analysis, anti-cathepsin B serum reacted with cathepsin B, but not with cathepsin H, indicating that the three thiol proteinases are distinct. Immunoelectrophoresis using a mixture of anti-cathepsin B and anti-cathepsin H showed that the precipitin line with cathepsin B moved faster to the anode than with cathepsin H. Immunological diffusion with antisera indicated that rat liver cathepsin B and H were immunologically identical with cathepsins B and H from rat kidney, lung, spleen, brain, and heart, but different from cathepsin B or H from human or rabbit liver.