pH-jump induced α-helix folding of poly-l-glutamic acid

• DOI: 10.1016/j.chemphys.2012.11.023
• Publication Date: 2012-12-27T03:02:00Z
• Authors: Mateusz L. Donten; Peter Hamm
• Keywords: Helix (gastropod); Folding (DSP implementation); Glutamic acid; Residue (chemistry); Biomolecule; Amide

Abstract pH jumps are a truly biomimetic technique to initiate non-equilibrium dynamics of biomolecules. In this work, the pH jump induced α-helix folding of poly- l -glutamic acid is investigated upon proton release from o-nitrobenzaldehyde. The aim of this work is twofold: On the one hand, design criteria of pH jump experiments are discussed, on the other hand, the folding mechanism of poly- l -glutamic acid is clarified by probing the IR response of the amide I band. Its folding kinetics is studied in dependence of the starting pD, the size of the pD jump and the length of the helix. While no dependence on the first two parameters could be detected, the folding time varies from 0.6 μs to 1.8 μs for helix lengths of 20 residue to 440 residue, respectively. It converges to a long-length limit at about 50 residue, a result which is attributed to a nucleation–propagation mechanism.