I prepared the protein with histidine tag in bacterial cell and purified
with Ni resin.
For the quantitation of my protein, I check the UV absorption.
Surprisingly, the maximun absorbance was at 260 nm instead of 280 nm
and the absorbance was slightly increased comparing the real concentration
of the protein.
Is this usual case?
I think that my protein has no significant nucleic acid contamination.
And the buffer contains 1 mM DTT,
The sample buffer was used for baseline of UV absorbance.
I didn't know the reason...
Thanks and happy new year...!