Tianyu,
You might try UV absorbance at 205 nM, where the protein backbone is the
absorbing moiety -- not aromatic side chains.
The Clore lab web site hosts a calculator that will estimate an E(205)
from an amino acid sequence (http://spin.niddk.nih.gov/clore/ , link on
the left hand side of the homepage).
This option has proved very helpful in a couple of situations
(coiled-coils, peptides, in particular), but be warned that many common
buffer components (HEPES, MES, DMSO) absorb very strongly at this
wavelength.
Sincerely,
ths
On 3/10/2015 4:49 PM, Gmail wrote:
Dear all,
I have a (heavily and heterogeneously) glycosylated protein that has
very low OD280 absorption. I wondered whether the glycans will have
any effect on the accuracy of BCA or Bradford assay. Amino acid
analysis doesn’t seem to be any better because carbohydrates will
interfere with sample analysis and quantification. Any suggestion
about other methods that we could try to measure the concentration of
this protein? Much appreciated!
Best,
Tianyu
--
Macromolecular Biophysics Resource
Department of Biophysics
UT Southwestern Medical Center, ND10.202
214.645.6350
http://biophysics.swmed.edu/MBR/main/
http://biophysics.swmed.edu
