[RASMB] physical origin of baseline offset in SediQ

[Wei Cheng]

Dear Rasmbers,

here is a question that has been in my mind since I used
sedimentation equilibrium. I read from an article written
by John Philo published in Methods in Enzymology V321, 100-120
which said that 0.01-0.02 AU seems to be typical for XL-A,
and I just wonder the physical factors that contribute to
baseline offsets. Things I read from literature, for example,
buffer absorbance, it does not make sense to me because the
data from XL-A is already after substraction of buffer blank;
another term, non-sedimenting species, appears a vague concept
to me and I would appreciate it greatly if someone can give
me more explanations.

Wei

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Wei Cheng
Dept. of Biochemistry & Molecular Biophysics
Box 8231, Washington University School of Medicine
660 S. Euclid Ave.
St. Louis, MO 63110
Daytime phone: 314-362-4394
Evening phone: 314-457-0900
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