Harada Akihito, Azakami Hiroyuki, Kato Akio
Department of Biological Chemistry, Yamaguchi University, Japan.
Biosci Biotechnol Biochem. 2008 Jun;72(6):1523-30. doi: 10.1271/bbb.80032. Epub 2008 Jun 7.
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.
构建了长螺旋B和C中的稳定和不稳定突变型溶菌酶，以评估螺旋在pH 2时对淀粉样纤维形成的影响。B螺旋中的稳定突变体N27D和不稳定突变体K33D在淀粉样纤维形成方面没有变化。相比之下，C螺旋中的稳定突变体N93D和不稳定突变体K97D在淀粉样纤维形成行为上表现出很大差异。稳定突变体N93D表现出较长的聚集滞后阶段并抑制了淀粉样纤维的形成，而不稳定突变体K97D表现出较短的聚集滞后阶段并加速了淀粉样纤维的形成。这些结果表明，长C螺旋主要参与溶菌酶淀粉样形成过程中α螺旋到β折叠的转变。
