Studies on the chromozyme TH-cleaving activity of human serum
Keller, H.; Keller, B.; Wolf, V.
Journal of Clinical Chemistry and Clinical Biochemistry 16(10): 571-578
1978
ISSN/ISBN: 0340-076X PMID: 712338 Document Number: 129481
As a rule, human and animal sera cleave the chromogenic substrate TH (Tos-Gly-Pro-Arg-pNa .cntdot. HCI). It is not normally cleaved by citrate-plasma, EDTA-plasma, heparin-plasma, urine, or CSF. During the investigation of the fundamental reasons for these differences, the cleavage rate by the serum of healthy blood donors, or patients without anticoagulant treatment, showed very wide variations. There was no significant difference between men and women. In the upper and lower extremes of cleavage activity in the blood of patients, there was no correlation with any diagnosis, condition or symptoms. In patients treated with anticoagulants, there was only a very rough correlation between the coagulation value of the citrate-plasma and the cleaving activity in the serum. The individual variation from day to day showed a scatter that was as much as 8-fold in individual cases. The conditions of blood sampling appeared to have a large influence on the serum activity, but it was never possible to obtain similar serum activities for different samples from 1 donor, simply by standardization of the sampling procedure. The chromozym TH-cleaving activity in the serum was more stable to storage than that of human thrombin. It was not inhibited by heparin and it was not adsorbed by barium sulfate or aluminium hydroxide. Sera with high chromozym TH-cleaving activities did not convert fibrinogen into fibrin. The electrophoretic behavior of the chromozym TH-cleaving activity was markedly different from that of human thrombin, and its Km was much lower. By immunoprecipitation, the chromozyme TH-cleaving activity was the property of a complex of thrombin and .alpha.2-macrogloublin.