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首页> 外文期刊>Biochemistry >Fractal Kinetic Behavior of Plasmin on the Surface of Fibrin Meshwork
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Fractal Kinetic Behavior of Plasmin on the Surface of Fibrin Meshwork

机译：纤溶酶在纤维蛋白网表面的分形动力学行为

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摘要

Intravascular fibrin clots are resolved by plasmin acting at the interface of gelphase substrate and fluid-borne enzyme. The classic Michaelis-Menten kinetic scheme cannot describe satisfactorily this heterogeneous-phase proteolysis because it assumes homogeneous well-mixed conditions. A more suitable model for these spatial constraints, known as fractal kinetics, includes a time-dependence of the Michaelis coefficient K_m ~F = K_(m0)~F (1 + t)~h, where h is a fractal exponent of time, t. The aim of the present study was to build up and experimentally validate a mathematical model for surface-acting plasmin that can contribute to a better understanding of the factors that influence fibrinolytic rates. The kinetic model was fitted to turbidimetric data for fibrinolysis under various conditions. The model predicted K_(m0)~F = 1.98 μM and h = 0.25 for fibrin composed of thin fibers and K_(m0)~F = 5.01 μM and h = 0.16 for thick fibers in line with a slower macroscale lytic rate (due to a stronger clustering trend reflected in the h value) despite faster cleavage of individual thin fibers (seen as lower K_(m0)~F). ε-Aminocaproic acid at 1 mM or 8 U/mL carboxypeptidase-B eliminated the time-dependence of K_m~F and increased the lysis rate suggesting a role of C-terminal lysines in the progressive clustering of plasmin. This fractal kinetic concept gained structural support from imaging techniques. Atomic force microscopy revealed significant changes in plasmin distribution on a patterned fibrinogen surface in line with the time-dependent clustering of fluorescent plasminogen in confocal laser microscopy. These data from complementary approaches support a mechanism for loss of plasmin activity resulting from C-terminal lysine-dependent redistribution of enzyme molecules on the fibrin surface.
机译：纤溶酶通过作用于凝胶相底物和液体传播的酶的界面而溶解血管内纤维蛋白凝块。经典的Michaelis-Menten动力学方案无法令人满意地描述这种异相蛋白水解过程，因为它假设均质的充分混合条件。对于这些空间约束更合适的模型称为分形动力学，其中包括迈克尔斯系数K_m〜F = K_（m0）〜F（1 + t）〜h的时间相关性，其中h是时间的分形指数， t。本研究的目的是建立并实验验证表面作用纤溶酶的数学模型，该模型可有助于更好地理解影响纤溶酶速率的因素。动力学模型适合于在各种条件下进行纤维蛋白溶解的比浊数据。该模型预测由细纤维组成的纤维蛋白的K_（m0）〜F = 1.98μM，h = 0.25，对于粗纤维，K_（m0）〜F = 5.01μM，h = 0.16，较慢的宏观分解速率（由于尽管单个细纤维的裂解速度更快（见较低的K_（m0）〜F），但在h值中仍显示出较强的聚集趋势。 1 mM或8 U / mL羧肽酶B的ε-氨基己酸消除了K_m〜F的时间依赖性，并增加了裂解速率，提示C端赖氨酸在纤溶酶的逐步聚集中发挥了作用。分形动力学概念得到了成像技术的结构支持。原子力显微镜显示在纤维蛋白原图案化表面上的纤溶酶分布有显着变化，这与共聚焦激光显微镜中荧光纤溶酶原的时间依赖性聚类一致。这些来自补充方法的数据支持了纤维蛋白表面上酶分子的C端赖氨酸依赖性重新分布导致纤溶酶活性丧失的机制。

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