Purification of a Trypsin-Type Protease from Human Umbilical Vein Endothelial Cells Which Is Highly Sensitive to the Kunitz Inhibitor Domain Peptide of Alzheimer’s Disease Amyloid Protein Precursor

Abstract

A trypsin-type protease was purified to enzymatic homogeneity from human umbilical vein endothelial cells by sequential affinity chromatographies. The enzyme specifically hydrolyzed dibasic substrates with leucine at the P3 positions, but scarcely hydrolyzed the other substrates tested. The enzyme was strongly inhibited by the Kunitz inhibitor domain peptide of Alzheimer’s disease amyloid protein precursor (Ki value, 0.35 nM) and by the microbial inhibitors leupeptin and anti-pain. These results, together with a previous finding of a significant increase in the expression of Alzheimer’s amyloid protein precursors (βAPPs) with the Kunitz inhibitor domain in Alzheimer’s disease, suggest that the activity of the trypsin-type protease is suppressed by an increase of βAPPs with inhibitor activity in Alzheimer’s disease, resulting in aberrant intracellular protein catabolism including degradation of βAPPs and β-protein deposition.

Serine protease and phenoloxidase activities in hemocytes of Biomphalaria glabrata snails with varying susceptibility to infection with the parasite Schistosoma mansoni

“…The hemocyte protease is of the serine class as demonstrated by our inhibition experiments, in particular with the serine protease inhibitors antipain (Nishikata et al 1989;Kido et al 1993) and aprotinin (Baciewicz 1998;Brinkmann et al 1997). The snail protease had a molecular mass of 28 kDa and this was clearly higher than the homologous enzyme from human neutrophils (around 24 kDa).…”

Biochemical comparison of the serine protease (elastase) activities in cercarial secretions from Trichobilharzia ocellata and Schistosoma mansoni

“…The enzyme activity was inhibited by PMSF and aprotinin, which are selective inhibitors for serine proteases (Powers and Harper 1986;Brinkmann et al 1997;Baciewicz 1998). Inhibition of the enzyme with anti-pain supports its trypsin-like activity (Nishikata et al 1989;Kido et al 1993). This is also the first comparison with the serine protease activity in CSs from S. mansoni.…”