Kinetics of the inhibition of human leucocyte elastase by eglin from the leech Hirudo medicinalis

The rate constants for the inhibition of human leucocyte elastase by eglin from the leech Hirudo medicinalis were determined by using a pre-steady-state kinetic approach. kon and koff for complex-formation and dissociation were 1 × 10(6)M-1 X S-1 and 8 × 10(-4)S-1 respectively. Ki was calculated as the ratio koff/kon = 8 × 10(-10)M, the binding of eglin to elastase was reversible and the inhibition mechanism was of the fully competitive type. The mechanistic properties of the system and the biological significance of the rate constants are discussed.