DYNAMICS OF POLYGLUTAMIC ACIDS IN ALPHA-HELICAL AND COIL STATES - COMPARISON WITH DYNAMICS OF SOME GLOBULAR-PROTEINS - RAYLEIGH-SCATTERING OF MOSSBAUER RADIATION (RSMR) DATA

The classical model system, poly-L-glutamic acid (poly-Glu), was inves tigated in a disordered coil state (at pH = 7.0) and in helix state (a t pH = 2.0) by the RSMR technique. By considering that the coil state of poly-Glu models unfolded (random coil) state and alpha-helix state models the fluctuating secondary structure (during consequent folding of protein), a comparative analysis of the dynamical properties of pol y-Glu in different states with the dynamical properties of different p roteins in the native state (alpha-helical myoglobin and HSA, partiall y beta-sheet lysozyme) and in intermediate (molten globule) state (alp ha-lactalbumin) was performed. This comparison brings some unpredicted results: native alpha-helical proteins behave close to random coil, n ative partially beta-sheet proteins behave close to fluctuating second ary structure (alpha-helix) and the dynamic behaviour of molten-globul e state (partially beta-sheet alpha-lactalbumin) is not different from the behaviour of lysozyme and much more rigid than that of native alp ha-helical proteins.