Amyloid fibril formation of hen lysozyme depends on the instability of the C-helix (88-99).
Stable and unstable mutant lysozymes in long helices B and C were constructed to evaluate the effect of the helices on amyloid fibril formation at pH 2. Stable mutant N27D and unstable mutant K33D in the B-helix did not change in amyloid fibril formation. In contrast, stable mutant N93D and unstable mutant K97D in the C-helix showed big differences in behavior as to amyloid fibril formation. Stable mutant N93D showed a longer lag phase of aggregation and suppressed the amyloid fibril formation, whereas unstable mutant K97D showed a shorter lag phase of aggregation and accelerated amyloid fibril formation. These results suggest that the long C-helix is involved mainly in the alpha-helix to beta-sheet transition during amyloid formation of lysozyme.
Department of Biological Chemistry, Yamaguchi University, Japan.
Akihito
A
Harada
Hiroyuki
H
Azakami
Akio
A
Kato
D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002645:Chickens / Q000378:metabolism*; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013696:Temperature
D000682:Amyloid; D009113:Muramidase