Release of [hydroxyproline 3]-kinins by tissue kallikreins of pig, rat and man

Abstract

To determine the susceptibility of kininogens containing the recently described [Hyp 3]-bradykinin moiety to cleavage by tissue kallikreins, we have studied the release of [Hyp 3]-kinins from heat inactivated human plasma by purified tissue kallikreins. Kallikreins from man and pig were employed and compared with purified rat urinary kallikrein which is known to have a different cleavage specificity. Kinins released were separated by a modified reversed phase HPLC method and quantitated by bioassay and radioimmunoassay. Human urinary kallikrein and hog tissue kallikreins released 85–90% of the total kinins as Lys-bradykinin and 10–15% as [Hyp 3]-Lys-bradykinin. In contrast, rat urinary kallikrein released 77% as bradykinin, 22% as [Hyp 3]-bradykinin and negligible amounts of [Hyp 3]-Lys-bradykinin from the identical substrate source indicating that rat tissue kallikreins prefer the Lys-Arg-bond within both unhydroxylated and hydroxylated kininogens. Therefore, hydroxylation of human kininogens apparently does not affect their ability to serve as substrates for tissue kallikreins with different cleavage specificities.