univ0938 at herald.ox.ac.uk
Wed Jan 15 07:41:19 EST 2003
On Wed, 15 Jan 2003, Dr Engelbert Buxbaum wrote:
> If true concentrations are required, Kjedal ashing may be used (that
> requires a lot of material), alternatively it is possible to calculate
> the absorbance of a protein at 280 nm from its amino acid composition,
> if the latter is known.
also, you can measure the absorbance at 214 nm, which is due to the
peptide bonds and is thus independent of composition. however, i think you
need rather specialised instruments and methods to do it, involving a
far-UV spectrophotometer, degassed buffers and whatnot. it's routinely
used to monitor the output from HPLC systems, but not for much else.
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