ANS Fluorescence

Mark Jason Logan mjlogan at
Wed Nov 16 13:13:38 EST 1994

Hello again,
I am currently working with a de novo designed helical bundle protein.  I
have examined the fluorescence behavior of 1-anilino-8-naphthalene
sulfonate in the presence of my protein as a function of pH.  At pH 2.3
the fluorescence spectrum is characterized by a sizeable increase in
intensity and a blue shift in the wavelength of maximal emission.  As the
pH is lowered to 1.8 the fluorescence intensity is increased but red
shifted by approximately 30 nm (relative to sample at pH 2.3).  Now I
realize that quantum yield and emission maxima are related to a variety of
factors such as fluorophore rigidity, solvent relaxation, and the
existance of two excited state species what I would like to know is how do
this factors contribute to the fluorescence of ANS.  I have read in the
literture that for 2-p-toluidinylnaphthalene-6-sulfonate the shift of
emission maxima is related to solvent relaxation and hence micorpolarity
whereas the quantum yield is effected by the conformational freedom or
microviscosity experienced by the probe.  Incidentally, with regards to
the effects of microviscosity on quantum yield I have seen several
conflicting reports where no effect on the quantum yield due to
microviscosity was observed. Go figure?

Any comments would be appreciated since I am in the process of writing my
thesis and would like to get a better handle on this ASAP.



P.S. please e-mail replies to mjlogan at

More information about the Proteins mailing list