[Temperature effect on the conformation state of fibrinogen and its derivatives]

The temperature dependence of spectral parameter B for fibrinogen, monomer fibrin, D and E fragments is examined by the method of ultraviolet fluorescence. Besides denaturation transition I (49 degrees C), conformational transition II (11-16 degrees C, depending on the sample) is observed in fibrinogen and its D fragment when temperature changes from 2 to 56 degrees C. Temperature transition II is reversible, sensitive to the ionic strength (its rise causes the transition temperature drop). Transition temperature of D fragment always correlates with that of fibrinogen, from which the fragment is obtained. Similarity in complex dependence of the B value on temperature for D fragment and fibrinogen is an additional proof of their structural likeness. No structural transitions are observed with a temperature rise up to 56 degrees C in E fragment. The ability of fibrinogen to inhibit self-assemblage of fibrin changes in the studied temperature intervals. A sharp transition from the acceleratory to inhibitory effect of fibrinogen on fibrin self-assemblage is registered at a temperature of about 11 degrees C. This change might be connected with structural transition II.