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The effect of 6-aminohexanoic acid and fucoidan on the activation of glutamic plasminogen by streptokinase

Harris, G.; Doctor, V. M.

Blood Coagulation & Fibrinolysis: June 2002 - Volume 13 - Issue 4 - p 355-359
Original Articles

Studies were conducted on the effect of 6-aminohexanoic acid (6-AH) or fucoidan on the activation of glutamic plasminogen (glu-plg) by streptokinase using 0.05 mol/l Tris buffer containing a physiological concentration of NaCl. In contrast to the earlier reports where no NaCl was added to the buffer solution, addition of 6-AH enhanced the initial rate while the inhibition by fucoidan was not affected. Double reciprocal plots of the activation of glu-plg by streptokinase in the presence of 6-AH showed an increase in Vmax, but no change in Km. However, the addition of fucoidan showed a decrease in Vmax, but no change in Km. To determine whether the stimulatory effect of 6-AH was specifically directed towards glu-plg or streptokinase, the ratios of the initial rate of plasmin generation in the presence of 6-AH over the controls were plotted against the inverse of the volume fraction of glu-plg or streptokinase after serial dilutions. The results indicated that the dilutions of glu-plg, but not of streptokinase, influenced the ratios, suggesting an interaction of 6-AH with glu-plg. Similar experiments were conducted to determine the mechanism of inhibition of streptokinase by fucoidan. The results indicated that fucoidan was interacting with streptokinase, but not with glu-plg. Circular dichroism studies of glu-plg in the near-ultraviolet spectra (250–308 nm) showed that addition of 6-AH enhanced the spectra in the region around certain chromophores, which reflected conformational changes. On the contrary, the far-ultraviolet spectra were almost identical.

The authors are with the Chemistry Department of Prairie View A University, Texas, USA.

(Received 24 September 2001

revised 13 February 2002 accepted 15 February 2002)

Address correspondence to V. M. Doctor, P.O. Box 4107, Prairie View A University, TX 77446, USA. Tel: (+1) 936 857 2617; fax: (+1) 936 857 2546; e-mail:

Sponsorship: These studies were supported by NIGMS Grant # 08094.

© 2002 Lippincott Williams & Wilkins, Inc.