Further studies of the turnover of dog antithrombin III. Study of 131I-labelled antithrombin protease complexes.
Fresh plasma containing 131I-antithrombin III (*I-AT) was coagulated and incubated at 37 degrees C for 2 hr. A "complex peak," separated on heparin-agarose contained AT and *I-AT antigen but no heparin cofactor activity. Crossed immunoelectrophoresis showed only AT complexes. SDS PAGE showed 80% of the *I-AT in a major band (approximately 80,000 daltons), 15% in a minor band (approximately 100,000 daltons) and the rest in trace bands (approximately 60,000 and/or 115,000 daltons). Ammonia treatment of the complex peak released alpha-thrombin. After i.v. injection 80% of the complexed *I-AT, chiefly as the major band, left the plasma with t 1/2 approximately 15 min and was almost immediately catabolized to low molecular weight breakdown products. A major catabolic site was the liver. A simple kinetic model describes the findings approximately.
D000818:Animals; D000990:Antithrombin III / Q000378:metabolism*; D002847:Chromatography, Agarose; D004285:Dogs; D005170:Factor X / Q000378:metabolism*; D015951:Factor Xa; D007123:Immunoelectrophoresis, Two-Dimensional; D007457:Iodine Radioisotopes; D013917:Thrombin / Q000378:metabolism*; D013997:Time Factors; D014018:Tissue Distribution
D007457:Iodine Radioisotopes; D000990:Antithrombin III; D005170:Factor X; D013917:Thrombin; D015951:Factor Xa