Studies on the labeling of streptokinase with 99mTc for use as a radiopharmaceutical in the detection of deep-vein thrombosis: concise communication.
Streptokinase was labeled with 99mTc using both stannous chloride and stannous pyrophosphate as reducing agents. Sixty to seventy-five percent of the 99m Tc was incorporated into streptokinase using stannous chloride as a reducing agent at pH 1-2, wheras 50-60% was incorporated using stannous pyrophosphate at neutral pH. Increasing the pH from 2 to 7 in the presence of stannous chloride caused the release of 15-20% of the protein-bound 99mTc. Incorporation of 99mTc into protein was relatively slow: labeling required 2-3 hr at room temperature. The concentration of stannous pyrophosphate required for optimum labeling varied between 10(-5) and 10(-2) M. Polyacrylamide-gel electrophoresis showed that the filler substance in commercial streptokinase was also labeled with 99mTc. However pure streptokinase gave a homogenous protein band after polyacrylamide-gel electrophoresis. This protein band coincided with the peak of streptokinase-bound 99mTc. The results obtained may partially explain why 99mTc-labeled streptokinase lacks the necessary specificity for the satisfactory location of blood clots in vivo.
D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007553:Isotope Labeling; D013300:Streptokinase / Q000378:metabolism; D013667:Technetium; D013927:Thrombosis / Q000175:diagnosis*; D014001:Tin / Q000378:metabolism; D014003:Tin Polyphosphates / Q000378:metabolism
D014003:Tin Polyphosphates; D013667:Technetium; D014001:Tin; D013300:Streptokinase