Kinetics of fibrin oligomer formation observed by electron microscopy

Fibrin oligomers, obtained by interrupting the polymerization of fibrinogen at early stages with a thrombin inhibitor, were examined by electron microscopy. The lengths of the various oligomers were determined and histograms were constructed to show their distribution. The length distribution agreed with a theory based on the assumption that thrombin releases the second A peptide more rapidly than the first, with a ratio of the release rates for the two peptides which is qualitatively in agreement with that deduced from oligomer size distributions obtained by agarose gel electrophoresis.