Inhibition of human tissue kallikrein by alpha 1-proteinase inhibitor

Tissue kallikreins, human urinary and pancreatic kallikrein, were inhibited by alpha 1-proteinase inhibitor, but the other inhibitors in plasma could not inhibit kallikrein activity towards a synthetic substrate. The kallikrein-inhibitor complex was identified by Sephadex G-150 gel filtration. The inhibition rate of urinary kallikrein by alpha 1-proteinase inhibitor was smaller than that of pancreatic kallikrein, and a less acidic subform of kallikrein was inhibited more rapidly than the more acidic one. Moreover, asialo-kallikrein was inhibited more rapidly than native kallikrein.