Fluorescence probe of polypeptide conformational dynamics in gas phase and in solution

Fluorescence measurements of polypeptides derivatized with the fluorescent dye BODIPY TMR have been used to probe the polypeptide conformational dynamics as a function of temperature and charge state. Measurements of (BODIPY TMR)-[Pro]n-Arg-Trp and (BODIPY TMR)[Gly-Ser]m-Arg-Trp have been performed for charge states 1+ and 2+ of n= 4 and 10 and m= 2 and 5. The 2+ charge states of both of these polypeptides exhibit similar temperature dependences for equal chain lengths (n= 4, m= 2 and n= 10, m= 5) and suggest conformations dominated by Coulomb repulsion. In the absence of such Coulomb repulsion, the 1+ charge state conformations appear to be characterized by the flexibility of t i i i t ©