A New Method for the Determination of Human Urinary Kallikrein Activity Using an Immunoadsorption Technique

A new method for the determination of urinary kallikrein activity was developed. A polystyrene bead coated with anti-human urinary kallikrein antibody was used, with prolyl-phenylalanyl-arginyl-4-methylcoumaryl-7-amide as a substrate. The proposed method is simpler, more accurate, and more specific to urinary kallikrein than the conventional method. Coefficients of variation for within-day precision and for day-to-day precision were 9.1% (n=20) and 14.4% (n=7), respectively, and recovery was 102±2.5% (n=10). The enzyme activities in urine from patients with renal failure and hypertension were lower than those in urine from normal subjects, but the activity in urine from patients with nephrotic syndrome was higher.