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The helical alanine controversy: an (Ala)6 insertion dramatically increases helicity.

ABSTRACT: Employing chemical shift melts and hydrogen/deuterium exchange NMR techniques, we have determined the stabilization of the Trp-cage miniprotein due to multiple alanine insertions within the N-terminal alpha-helix. Alanine is shown to be uniquely helix-stabilizing and this stabilization is reflected in the global fold stability of the Trp-cage. The associated free energy change per alanine can be utilized to calculate the alanine propagation value. From the Lifson-Roig formulation, the calculated value (wAla = 1.6) is comparable to those obtained for short, solubilized, alanine-rich helices and is much larger than the values obtained by prior host-guest techniques or in N-terminally templated helices and peptides bearing long contiguous strings of alanines with no capping or solubilizing units present.

SUBMITTER: Lin JC

PROVIDER: S-EPMC3870188 | biostudies-literature | 2004 Oct

REPOSITORIES: biostudies-literature

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The helical alanine controversy: an (Ala)6 insertion dramatically increases helicity.

Lin Jasper C JC Barua Bipasha B Andersen Niels H NH

Journal of the American Chemical Society 20041001 42

Employing chemical shift melts and hydrogen/deuterium exchange NMR techniques, we have determined the stabilization of the Trp-cage miniprotein due to multiple alanine insertions within the N-terminal alpha-helix. Alanine is shown to be uniquely helix-stabilizing and this stabilization is reflected in the global fold stability of the Trp-cage. The associated free energy change per alanine can be utilized to calculate the alanine propagation value. From the Lifson-Roig formulation, the calculated ...[more]

PMID: 15493925

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