Molar extinction coefficient of a protein at 280 nm.
chrisp at rschp1.anu.edu.au
Sun Mar 19 21:06:52 EST 1995
In article writes:
>From: madi at biocell.fundp.ac.be (Marc DIEU)
>Subject: Molar extinction coefficient of a protein at 280 nm.
>Date: 16 Mar 1995 13:00:44 GMT
>Is it possible to determine the molar extinction coefficient at 280 nm
>of a given protein (epsilon 280 nm prot.) simply by additionning the
>individual molar extinction coefficients of the different aromatic
>residues which compose the sequence of the protein ? Is it correct or
It's possible to get an estimate. Cantor and Schimmel (Biophysical
Chemistry, part 2, 1980) give a formula for estimating extinction
coefficients based solely on aromatic amino acid content of a protein.
Its accurate to about +/- 25%. Gill and von Hippel (Anal. Biochem.
182:319-326 (1989)) have also published a paper on this. They consider
the contributions of trp, tyr and cys to absorbance. Phe and his make
almost no contribution. The calculated values are all within about
10% of the measured values for 18 "normal" globular proteins.
Chris Penington The opinions expressed are mine. NOT
Research School of Chemistry, those of the school *or* the university
Australian National University,
Canberra, ACT 0200 chrisp at rschp1.anu.edu.au
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