[Protein-analysis] Re: Bradford Assay !

StewJW stewjw at gmail.com
Fri Aug 4 09:52:29 EST 2006

Why not try the easy to use Quant-it kits from invitrogen which uses a
fluorescent dye and can be used in a microplate as well as a cuvette
format (Q33210). Even easier use the cheap new Qubit fluorometer
(Q32857, approx £350), which uses LED light technology, with the Qubit
Protein Quant-it kit (Q33211, £35)--life is too short to be messing
about with Bradford & Lowry assays these days. The kit each contains a
proprietary fluorescent dye, which binds specifically to proteins.
When in aqueous solution the dye emits a low fluorescence signal that
increases on binding.

All the Quant-it kits (including ones for ssDNA, dsDNA & RNA) are
compatible with reducing reagents and the presence of a wide range of
contaminants, which are listed in the back of their respective kit
manuals. The sensitivity, including the DNA/RNA kits, used with the
Qubit device are

Kit	                                  Assay range	        Sample
Quant-iT DNA HS Assay	      0.2 - 100 ng	     10 pg/mL - 100 ng/mL
Quant-iT DNA BR Assay	      2 - 1000 ng	     100 pg/mL - 1 mg/mL
Quant-iT RNA Assay	                      5 - 100 ng	     250 pg/mL
- 100 ng/mL
Quant-iT Protein Assay*	      0.25 - 5 mg	     12.5 ug/mL - 5 mg/mL

If detergents are present, the bane of most protein assays, use the EZQ
Protein Quantitation kit R33200 which is adapted into microplate format
and involves a binding the protein to a membrane and washing to remove
contaminants, easier than it sounds.

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