Abstract
Intravascular fibrin clots are resolved by plasmin acting at the interface of gel-phase 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 KmF = Km0F(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 Km0F= 1.98 μM and h = 0.25 for fibrin composed of thin fibers and Km0F= 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 Km0F). ε-Aminocaproic acid at 1 mM or 8 U/mL carboxypeptidase-B eliminated the time-dependence of KmF 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.
| Original language | English |
|---|---|
| Pages (from-to) | 6348-6356 |
| Number of pages | 9 |
| Journal | Biochemistry |
| Volume | 53 |
| Issue number | 40 |
| DOIs | |
| Publication status | Published - okt. 14 2014 |
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ASJC Scopus subject areas
- Biochemistry
- Medicine(all)
Cite this
Fractal kinetic behavior of plasmin on the surface of fibrin meshwork. / Varjú, Imre; Tenekedjiev, Kiril; Keresztes, Z.; Pap, A.; Szabó, László; Thelwell, Craig; Longstaff, Colin; Machovich, R.; Kolev, K.
In: Biochemistry, Vol. 53, No. 40, 14.10.2014, p. 6348-6356.Research output: Article
}
TY - JOUR
T1 - Fractal kinetic behavior of plasmin on the surface of fibrin meshwork
AU - Varjú, Imre
AU - Tenekedjiev, Kiril
AU - Keresztes, Z.
AU - Pap, A.
AU - Szabó, László
AU - Thelwell, Craig
AU - Longstaff, Colin
AU - Machovich, R.
AU - Kolev, K.
PY - 2014/10/14
Y1 - 2014/10/14
N2 - Intravascular fibrin clots are resolved by plasmin acting at the interface of gel-phase 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 KmF = Km0F(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 Km0F= 1.98 μM and h = 0.25 for fibrin composed of thin fibers and Km0F= 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 Km0F). ε-Aminocaproic acid at 1 mM or 8 U/mL carboxypeptidase-B eliminated the time-dependence of KmF 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.
AB - Intravascular fibrin clots are resolved by plasmin acting at the interface of gel-phase 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 KmF = Km0F(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 Km0F= 1.98 μM and h = 0.25 for fibrin composed of thin fibers and Km0F= 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 Km0F). ε-Aminocaproic acid at 1 mM or 8 U/mL carboxypeptidase-B eliminated the time-dependence of KmF 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.
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U2 - 10.1021/bi500661m
DO - 10.1021/bi500661m
M3 - Article
C2 - 25222106
AN - SCOPUS:84908032479
VL - 53
SP - 6348
EP - 6356
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 40
ER -