Preparation and characterization of αC(FXIII) and αC(tTG) oligomers. (A) SDS-PAGE analysis of the recombinant αC domain fragment and its oligomers. The αC domain (lane 1) was covalently cross-linked with factor XIIIa (lane 2) or tTG (lane 4), and the resulting material was subjected to size-exclusion chromatography to separate high molecular mass fractions containing αC(FXIII) oligomers (lane 3) or αC(tTG) oligomers (lane 5); the right outer lane contains protein markers of the indicated molecular mass. (B-D) Electron microscopy of the rotary shadowed samples of the αC domain fragment (B) and its αC(FXIII) and αC(tTG) oligomers (C-D, respectively). Bar indicates 100 nm. (E-F) Higher magnification and contrast images of small portions of panels C and D, respectively, showing details of the branching polymers. Bar indicates 100 nm.