Premium
Effect of NaCl on the association of thrombin with heparin
Author(s) -
Oshima Genichiro,
Uchiyama Hideki,
Nagasawa Kinzo
Publication year - 1986
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360250402
Subject(s) - chemistry , heparin , thrombin , antithrombin , ternary complex , titration , ternary operation , inorganic chemistry , nuclear chemistry , chromatography , biochemistry , enzyme , platelet , medicine , computer science , programming language
Abstract The association of heparin with thrombin was investigated by fluorometric titration. A maximum of 25% of the fluorescence of fluorescein‐labeled heparin (FTC‐heparin) was quenched at thrombin saturation in the absence of NaCl. FTC‐heparin (H) associated tightly with thrombin (T) and the association constant of the ternary complex, H 2 T, formed in the absence of NaCl, was calculated to be 1.7 × 10 8 M −1 . However, the association was strongly influenced by the NaCl concentration, and the association constant of the equimolar complex, HT, formed in 0.15 M NaCl was found to be 1 × 10 6 M −1 . The first‐order rate constant, k app , for inactivation of thrombin by antithrombin III (AT III) and low‐affinity heparin (LA‐heparin) was comparable with that of high‐affinity heparin (HA‐heparin) in the absence of NaCl, but decreased with an increase in the concentration of NaCl. The decreased enhancement of the thrombin‐AT III reaction by LA‐heparin at high NaCl concentration appeared to result from a decreased association of thrombin with LA‐heparin, thus reducing the formation of the ternary complex, thrombin‐LA‐heparin‐AT III.