Charge invariant protein-water relaxation in GB1 via ultrafast tryptophan fluorescence.

ABSTRACT: The protein-water interface is a critical determinant of protein structure and function, yet the precise nature of dynamics in this complex system remains elusive. Tryptophan fluorescence has become the probe of choice for such dynamics on the picosecond time scale (especially via fluorescence "upconversion"). In the absence of ultrafast ("quasi-static") quenching from nearby groups, the TDFSS (time-dependent fluorescence Stokes shift) for exposed Trp directly reports on dipolar relaxation near the interface (both water and polypeptide). The small protein GB1 contains a single Trp (W43) of this type, and its structure is refractory to pH above 3. Thus, it can be used to examine the dependence of dipolar relaxation upon charge reconfiguration with titration. Somewhat surprisingly, the dipol

SUBMITTER: Biesso A 

PROVIDER: S-EPMC4004251 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature