Measuring peptide concentration

Emir Khatipov khatipovNO at NOuchicago.edu
Mon Mar 18 18:18:12 EST 2002


Use Protparam tool at www.expasy.ch/tools to calculate molar extinction
coefficient of your peptide and use it for your spectrophotometric
measurements. Peptides absorb light at 280nm even if they don't contain any
aromatic residues. I hope it is needless to say that you should use same 10%
DMSO in PBS as a reference. If you believe there are impurities in your
samples, I would suggest determining absorption spectra of your peptide
solutions at ~200-350nm (or at least 250-330nm). If your sample is pure, you
should see a nice peak at around 276-280nm. Be aware that peptide bond
absorbs at 214nm, but there might be a lot of interference from impurities
you may have in your sample.

Emir


"JB" <j.bukczynskiDELETE_ME at utoronto.ca> wrote in message
news:b87a9ugslasbigp8lm4dhkqc4p0soe0se7 at 4ax.com...
> Hi,
>
> Does anyone know how to measure peptide concentration using a
> spectrophotometer? I have it dissolved in 10% DMSO in PBS. Any help
> would be appreciated. Thanks,
>
> Jacob





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