title: Kinetic analysis provides insight into the mechanism of ribonuclease A oligomer formation.
abstract: Ribonuclease A forms a series of oligomers by 3D domain swapping, a possible mechanism for amyloid formation. Using experimental data, the Ribonuclease oligomerization process is analyzed to obtain estimates of individual equilibrium and microscopic rate constants. The results suggest several novel insights into Ribonuclease oligomer formation: (i) two dimers may combine to yield tetramers, (ii) the lower abundance of the cyclic trimer could be ascribed to the cis conformation of its Asn113-Pro114 peptide bonds, (iii) oligomers become the dominant species at very high protein concentrations or upon applying a modest tenfold increase in the equilibrium constants (iv) the rate constants for trimer and tetramer formation are faster than those of dimer formation and (v) glycosylation affects the relative populations of different trimer and tetramer species. By mass spectrometry, oligomers as large as tetradecamers are detected. These results are consistent with the proposal that 3D domain swapping is a mechanism for amyloid formation.
authors.affiliation: Instituto de Química Física "Rocasolano" (C.S.I.C.), Serrano 119, E-28006 Madrid, Spain.
authors.forename: Jorge P
authors.initials: JP
authors.lastname: López-Alonso
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gotte
authors.forename: Douglas V
authors.initials: DV
authors.lastname: Laurents
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D002417:Cattle; D019281:Dimerization; D007700:Kinetics; D013058:Mass Spectrometry; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000682:Amyloid; D012259:Ribonuclease, Pancreatic