[Distribution of aromatic amino acid residues according to the character of their microenvironment and the dynamics of the conformational properties of the protein molecule C1q]. / Raspredelenie aromaticheskikh aminokislotnykh ostatkov po kharakteru mikrookruzheniia i dinamicheskie konformatsionnye svoistva molekuly belka C1q.

The distribution of aromatic amino acid residues in the Clq molecule according to their microenvironment was studied by the methods of difference thermal and solvent perturbation spectroscopy, fluorescence and chemical modification. Out of the three tryptophan residues located in the globular part of A- chain one residue is completely exposed on the surface, while other two are only partially exposed to a solvent. Chemical modification of tryptophanyls significantly affects the hemolytic activity of Clq, that may evidence for the formation of immunoglobulin-binding sites with participation of A- chains as well as for the location of, at least, one of the three tryptophan residues in A- chain close to the immunoglobulin-binding site or even participation in the formation of the latter. The average rotation relaxation time of tryptophanyls estimated from the data on fluorescence is 210 +/- 10 ns. It specifies mobility of the globular and collagen parts of the molecule.

[Conformation changes in the mechanism of cryoprecipitation of human monoclonal immunoglobulin M]. / Izuchenie konformatsionnykh izmenenii v mekhanizme kriopretsipitatsii monoklonal'nogo immunoglobulina M cheloveka.

The role of conformational changes in the mechanism of cryoprecipitation of human monoclonal immunoglobulin M (IgM) was studied. It was demonstrated that the variable moiety of the Fab-region of cryo-IgM has a site which comprises 5 to 6 charged amino acid residues. This site is responsible for intermolecular electrostatic interactions which lead to the formation of a precipitate with a decrease in temperature. This interaction is cooperative and stabilized by dipole molecules of H2O. The chain growth during aggregation is nuclear. The primary nucleus contains three IgM macromolecules. stability of the three-molecule nucleus is provided for by 16--17 intermolecular links. Using circular dichroism and fluorescent methods, it was found that the formation of a cryoprecipitate is accompanied by ionic pair release and conformational changes.