[New data on the structure of fibrinogen]

The results of physical and chemical investigations show the closeness of fibrinogen to globular proteins, but some differences from globular proteins in certain characteristic features are found resulted from high asymmetry or high hydration of the molecule. The results of electron microscopy cannot be interpreted in a simple way, but nevertheless they show the presence of conformational mobility and existence of configurational isomers. The amino acid sequence of the most important parts of a fibrinogen molecule is known now: "the N-terminal disulphide knot" including peptides A and B being splitted by thrombin, and the part of the gamma-chain participating in covalent binding of fibrin. The study of plasmin and CNBr split products is a fruitful approach to the study of fibrinogen structure and the chemical models of fibrinogen are based on them. In the latest models the N-terminal parts of all 6 polypeptide chains of fibrinogen are located in the centre of a molecule, so the earlier concepts on monomeric fibrin polymerization in the end-to-end way must be reconsidered. None of the existing models produces a definite description of the functional properties of fibrinogen; the appearance of such a model is expected in the nearest future.