Dynamics of polyglutamic acids in alpha-helical and coil states. Comparison with dynamics of some globular proteins. Rayleigh scattering of Moessbauer radiation (RSMR) data

The classical model systems, poly-L-glutamic acid (poly-Glu), was investigated in a disordered coil state (at pH = 7.0) and in helix state (at pH = 2.0) by the RSMR technique. By considering that the coil state of poly-Glu models unfolded (random coil) state and α-helix state models the fluctuating secondary structure (during consequent folding of protein), a comparative analysis of the dynamical properties of poly-Glu in different states with the dynamical properties of different proteins in the native state (α-helical myoglobin and HSA, partially β-sheet lysozyme) and in intermediate (molten globule) state (α-lactalbumin) was performed. This comparison brings some unpredicted results: native α-helical proteins behave close to fluctuating secondary structure (α-helix) and the dynamic behaviour of molten-globule state (partially β-sheet α-lactalbumin) is not different from the behaviour of lysozyme and much more rigid than that of native α-helical proteins