Binding of heparin to human high molecular weight kininogen.
The binding of heparin to high molecular weight kininogen (H-kininogen) was analyzed by the effect of kininogen in decreasing the heparin-induced enhancement of the rate of inactivation of thrombin by antithrombin. The conditions were arranged so that the heparin-catalyzed antithrombin-thrombin reaction, monitored in the presence of the reversible thrombin inhibitor p-aminobenzamidine, followed pseudo-first-order kinetics and the observed rate constant (kappa obsd) varied linearly with the heparin concentration. In the absence of metal ions, H-kininogen minimally affected kappa obsd, measured at a constant concentration of heparin with high affinity for antithrombin (30 nM), at I = 0.15, pH 7.4 and 25 degrees C. However, at a saturating concentration of Zn2+ (10 microM), kappa obsd was reduced to 50% at approximately 20 nM H-kininogen and to that of the uncatalyzed reaction at greater than or equal to approximately 0.2 microM H-kininogen. Conversely, at a saturating concentration of H-kininogen (0.5 microM), kappa obsd was decreased to 50% at approximately 0.6 microM Zn2+ and to the kappa obsd of the uncatalyzed reaction at greater than or equal to 10 microM Zn2+. Other metal ions were effective in the order Zn2+ approximately Ni2+ greater than Cu2+ approximately Co2+ approximately Cd2+. The single-chain and two-chain forms of H-kininogen and the H-kininogen light chain reduced the heparin enhancement in the presence of Zn2+ to the same extent, whereas low molecular weight kininogen had no influence.(ABSTRACT TRUNCATED AT 250 WORDS)
Björk
I
I
Division of Biochemical Research, Henry Ford Hospital, Detroit, Michigan 48202.
Olson
S T
ST
Sheffer
R G
RG
Shore
J D
JD
D000991:Antithrombins / Q000378:metabolism; D002413:Cations, Divalent; D002846:Chromatography, Affinity; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007704:Kininogens / Q000378:metabolism*; D046911:Macromolecular Substances; D011485:Protein Binding; D013917:Thrombin / Q000378:metabolism
D000991:Antithrombins; D002413:Cations, Divalent; D007704:Kininogens; D046911:Macromolecular Substances; D006493:Heparin; D013917:Thrombin