Hypochlorite-induced oxidation of fibrinogen: Effects on its thermal denaturation and fibrin structure.

Background: Human fibrinogen, which plays a key role in plasma haemostasis, is a highly vulnerable target for oxidants. Fibrinogen undergoes posttranslational modifications that can potentially disrupt protein structure and function.

Methods: For the first time, by differential scanning calorimetry, dynamic and elastic light scattering and confocal laser scanning microscopy, the consequences of HOCl/OCl-induced oxidation of fibrinogen on its thermal denaturation, molecular size distribution and fibrin clot network have been explored.

Results: Within a wide range of HOCl/OCl concentrations (50-300 μM), the molecular size distribution remained unimodal; however, the average size of the hydrated molecules decreased. HOCl/OCl-induced oxidation of fibrinogen resulted in the diminished thermal stability of regions D and E. As evidenced by elastic light scattering and confocal laser scanning microscopy, HOCl/OCl caused the formation of abnormal fibrin with a decreased diameter of individual fibres.

Conclusions: The current results along with data from previous studies enable one to conclude that the effect of HOCl/OCl-mediated oxidation on the thermal stability of region D is influenced directly by oxidative damage to the D region structure. Since the E region is not subjected to oxidative modification, its structural damage is likely to be mediated by the oxidation of other protein structures, in particular α-helical coiled-coils.

General Significance: The experimental findings acquired in the current study could help to elucidate the consequences of oxidative stress in vivo on damage to the structure of fibrinogen/fibrin under the action of different ROS species.