RRC ID 41487
Author Matsunaga Y, Saito N, Fujii A, Yokotani J, Takakura T, Nishimura T, Esaki H, Yamada T.
Title A pH-dependent conformational transition of Abeta peptide and physicochemical properties of the conformers in the glial cell.
Journal Biochem J
Abstract In the present study we identified the epitopes of antibodies against amyloid beta-(1-42)-peptide (Abeta1-42): 4G8 reacted with peptides corresponding to residues 17-21, 6F/3D reacted with peptides corresponding to residues 9-14, and anti 5-10 reacted with peptides corresponding to residues 5-10. The study also yielded some insight into the Abeta1-42 structures resulting from differences in pH. An ELISA study using monoclonal antibodies showed that pH-dependent conformational changes occur in the 6F/3D and 4G8 epitopes modified at pH 4.6, but not in the sequences recognized by anti 1-7 and anti 5-10. This was unique to Abeta1-40 and Abeta1-42 and did not occur with Abeta1-16 or Abeta17-42. The reactivity profile of 4G8 was not affected by blockage of histidine residues of pH-modified Abeta1-40 and Abeta1-42 with diethyl pyrocarbonate; however, the mutant [Gln(11)]Abeta1-40 abrogated the unique pH-dependence towards 4G8 observed with Abeta1-40. These findings suggest that these epitopes are cryptic at pH 4.6, and that Glu(11) is responsible for the changes. We suggest that the abnormal folding of 6F/3D epitope affected by pH masked the 4G8 epitope. A study of the binding of metal ions to Abeta1-42 suggested that Cu(2+) and Zn(2+) induced a conformational transition around the 6F/3D region at pH 7.4, but did not affect the region when it was modified at pH 4.6. However, Fe(2+) had no effect, irrespective of pH. Abeta modified at pH 4.6 appeared to be relatively resistant to proteinase K compared with Abetas modified at pH 7.4, and the former might be preferentially internalized and accumulated in a human glial cell. Our findings suggest the importance of microenvironmental changes, such as pH, in the early stage of formation of Abeta aggregates in the glial cell.
Volume 361(Pt 3)
Pages 547-56
Published 2002-2-1
DOI 10.1042/0264-6021:3610547
PMID 11802784
PMC PMC1222337
MeSH Alzheimer Disease / metabolism Amino Acid Sequence Amino Acids / chemistry Amyloid beta-Peptides / chemistry* Antibodies, Monoclonal / metabolism Blotting, Western Cell Line Densitometry Enzyme-Linked Immunosorbent Assay Epitope Mapping Epitopes Histidine / chemistry Humans Hydrogen-Ion Concentration Iron / chemistry Molecular Sequence Data Neuroglia / cytology* Peptide Biosynthesis Protein Binding Protein Conformation Protein Structure, Tertiary Sequence Homology, Amino Acid Time Factors
IF 4.097
Times Cited 17
Human and Animal Cells