Insight into the mechanism of myosin-fibrin gelation induced by non-disulfide covalent cross-linking

Abstract

To explore the mechanism of non-disulfide covalent cross-linking between myosin and fibrin, the gel strength, texture parameters, rheological properties, protein conformation and microstructure and possible cross-linking sites were investigated during the gelling of myosin-fibrin gels. Higher ε-(γ-glutamyl)-lysine level in myosin-fibrin gels with transglutaminase significantly enhanced the textural properties, rheology properties and water holding capacity of myosin-fibrin gels, compared with pure myosin gel and myosin-fibrin gels with ehylenediaminetetraacetic acid; Fourier infrared spectra (FTIR) and circular dichroism (CD) spectra demonstrated that the structural transition from α-helix to β-sheet significantly was improved in myosin-fibrin gels with the addition of transglutaminase than other groups. Scanning electron microscopy revealed that high level of ε-(γ-glutamyl)-lysine cross-linking contributed to the formation of myosin-fibrin gels with a dense gel network structure with thick walls and low porosity. Myosin heavy chain was mainly involved in the cross-linking with α/β/γ-chains of fibrinogen; liquid chromatography-tandem mass spectrometry further demonstrated that Lys¹⁰⁸⁵ of myosin heavy chain was non-disulfide covalently bound to Gln¹⁹⁵ of fibrinogen to form "K-Q" isopeptide during the cross-linking of myosin-fibrin.

Keywords: Cross-linking sites; Fibrin; LC-MS/MS; Myosin; ε-(γ-glutamyl)-lysine bonds.