HYDROPHOBIC INTERACTIONS IN THE UROKINASE ACTIVE CENTRE

Abstract
In order to obtain information concerning the binding site of urokinase (EC 3.4.99.26) the inhibitory action of aliphatic ammonium and amidinium ions has been studied. The comparison between the corresponding Kivalues for urokinase and trypsin shows that although the two enzymes possess a hydrophobic binding pocket of presumably equal length, they differ mainly in their behaviour towards n‐alkylammonium ions with an alkyl chain longer than four methylene groups and towards benzylammonium and amidinium ions. This is an indication of a less rigid binding site in urokinase than in trypsin.