Ozone-induced damage of fibrinogen molecules: identification of oxidation sites by high-resolution mass spectrometry.

Fibrinogen is highly susceptible to oxidation compared to other plasma proteins. Fibrinogen oxidation damages its structure and affects the protein function. Ozone-induced oxidative modifications of the fibrinogen Aα, Bβ, and γ polypeptide chains upon addition of various amounts of the oxidiser were studied by mass spectrometry. Amino acid residues located on all three chains and main structural parts of the protein were revealed to be involved in oxidation. The αC-connector was shown to be most vulnerable to oxidation as compared to other structural parts while the E region turned out to be the most protected area of the protein. For the first time, it was established that numerous amino acid residues responsible for the conversion of fibrinogen to fibrin remain unaffected upon fibrinogen oxidation. The data obtained in this study indicate that none of the identified residues, which are considered crucial for the binding of both hole "a" and hole "b" to knob "A" and knob "B", respectively, as well as those responsible for the thrombin binding to fibrinogen E region, have been subjected to chemical alterations under moderate oxidation. The data on fibrinogen oxidation acquired in the current study enable one to assume that some of the structural fibrinogen parts and easily oxidisable residues could be endowed with antioxidant properties. New findings presented here could be essential for the detection of adaptive molecular mechanisms capable of mitigating the detrimental action of reactive oxygen species (ROS) on the functioning of oxidatively damaged fibrinogen. Data are available via ProteomeXchange with identifier PXD012046. Highlights Various oxidative modifications were detected in fibrinogen by mass spectrometry αC-connector has been shown to be most susceptible to oxidation E region proved to be least vulnerable to the action of the oxidising agent Some of the Met residues in the fibrinogen structure could operate as ROS scavengers.