Properties of canine tissue thromboplastins from brain, lung, arteries, and veins

Properties of the protein moieties of canine tissue thromboplastins (TTP's) from brain (BTTP), lung (LTTP), arteries (ATTP), AND VEINS (VTTP) were determined. The maximum specific activity of each protein moiety after its relipidation was obtained when the phospholipid-delipidated TTP ratio was 0.32 and was 1,395 U/mg BTTP, 1,130 U/mg LTTP, 630 U/mg VTTP, and 435 U/mg ATTP. The amino acid contents of the protein moieties of LTTP, ATTP, and VTTP were closely similar, but that of BTTP was significantly different. The Ouchterlony analysis showed that BTTP did not react at all with the antibody against VTTP, but that three other TTP's did and showed the reaction of complete identity. Then, the reactivity of 125-I-labeled TTP's with the anti-VTTP antibody was studied. The results showed that 0.79 +/- 0.01 (SD) % of [125I]BTTP, 10.24 +/- 0.5 (SD) % of [125I]LTTP, 19.4 +/- 0.2 (SD) % of [125I]VTTP, and 5.88 +/- 0.4 (SD) % of [125I]ATTP added were bound to the antibody in 2 h. Next, the molecular weight of each was determined by Sephadex G-200 filtration, which averaged 80,000 +/- 4,000 (SD) ([125I]BTTP), 113,000 +/- 5,000 (SD) ([125I]LTTP), 62,000 +/- 3,000 (SD) ([125I]ATTP), and 47,000 +/- 2,000 (SD) ([125I]VTTP). Finally, the plasma behavior of each was studied in four dogs. The plasma half-life averaged 8.1 +/- 0.24 (SD) h ([125I]BTTP), 14.6 +/- 0.5 (SD) h ([125I]LTTP), 7.38 +/- 0.48 (SD) h ([1252]ATTP), and 24.3 +/- 0.9 (SD) h ([125I]VTTP). These results indicate that the protein moieties of canine TTP's from brain, lung, arteries, and veins are closely similar in some aspects but dissimilar in others and are definitely not identical.