Avtor/Urednik		Jenko-Kokalj, Saša
Naslov		Strukturne študije oligomerov in amiloidnih fibril stefinov A in B
Tip		monografija
Kraj izdaje		Ljubljana
Založnik		Univerza v Ljubljani, Medicinska fakulteta
Leto izdaje		2004
Obseg		str. 55
Jezik		slo
Abstrakt		Under properly chosen conditions proteins in general form amyloid fibrils. Amyloid fibrils of different proteins share a common molecular skeleton, the protofilament core structure, which is a continuous beta-sheet helix. Two homologous proteins stefins A and B were chosen to study the mechanism of fibrillation from a structural point of view. Although topologically similar, they are subjected to different folding pathways. We demonstrated that both stefins share common structural features characteristic for other amyloid fibrils, but the conditions needed to undergo fibrillation differ. Analysis of three-dimensional structures of monomers and domain-swapped dimers suggest that major differences in stability of both homologues stem from arrangement of specific salt bridges, which fix alpha-helix to beta-sheet in stefin A monomeric and dimeric forms. Data from folding and fibrillation studies of stefins A and B and their mutants done by M. Kenig and results of oligomeric state studies of stefins led us to crystallize a stefin B point mutant P79S and a stefin B himeric mutant B37A. We solved the stefin B point mutant P79S crystal structure. The crystal structure revealed that stefin B point mutant P795 is a tetramer formed by two domain-swapped dimers. The three-dimensional structure of the tetramer and the dimensions of the stefin amyloid fibrils measured by atomic force microscopy gave us some insights into the mechanism of fibrillation. As a result of our investigation we propose that a tetramer is the next intermediate of fibrillation and that linear aggregation of tetramers takes place afterwards to form a protofibril. The linear aggregation model of tetramers will be subjected to further evaluation by mutational studies and to binding of oligomer specific antibodies which selectively recognize critical oligomers in the fibrillation process.
Deskriptorji		CYSTEINE PROTEINASE INHIBITORS AMYLOID BETA-PROTEIN RECOMBINANT PROTEINS PROTEIN STRUCTURE, SECONDARY TRANSFORMATION, GENETIC MICROSCOPY, ATOMIC FORCE X-RAY DIFFRACTION