[Structure-functional analysis of peptide P3 identical to gamma370-383 binding sites with integrin alphaIIbbeta3 in gammaC-domain of fibrinogen]. / Strukturno-funltsional'nyi analiz peptydu P3, shcho ie identychnym do gamma370-383-dilianky zv'iazuvannia z intehrynom alphaIIbbeta3 u gammaC-domeni fibrynohenu.

The interactions between platelet integrin alpha IIb beta 3 and fibrinogen (Fg) mediate a range of adhesive reactions, which are necessary for platelet aggregation and fibrin clot retraction. The binding site for alpha IIb beta 3 resides in the gamma C domain of Fg. In our previous work we have identified a novel binding site in the gamma C domain, gamma 370-383 (P3), for integrin alpha IIb beta 3 and have demonstrated that the P3 sequence together with the C-terminal gamma C sequence 408AGDV411 accounts for the full binding of alpha IIb beta 3. In our present study, in order to define the amino acid residues in P3 involved in the interaction with alpha IIb beta 3, we have used SPOT-synthesis analyses. Libraries consisting of peptides covering P3 were created and probed with radiolabeled alpha IIb beta 3. Screening of the libraries showed that several positively charged residues may be critical for interaction of P3 with integrin alpha IIb beta 3.

[Studies in the fibrinogen molecule D fragment inactivation protecting fragment]. / Doslidzhennia reaktsii inaktivatsii fragmenta D mlekuli fibrinogenu fragmentom-protektorom.

The interaction was studied between two fragments of bovine fibrinogen isolated from its tryptic hydrolysate: the D fragment, an inhibitor of fibrin-monomer polymerization, and the protector, a fragment inactivating the D fragment. This reaction is relatively rapid: it is completed for several minutes at room temperature and at 37 degrees and is slowed down at 5 degrees. However, the reached level of the D fragment inactivation does not depend upon temperature (within a range from 5 degrees to 37 degrees). Dilution of the incubation mixture under applied conditions caused no dissociation of the D fragment-protector complex. Inactivation of the D fragment by the protector depends on the solution ionic strength; ionic strength 0.13-0.16 is optimal.