calculating extinction c

Spencer Fisk fisk at
Thu Nov 17 12:47:17 EST 1994

        Reply to:   RE>calculating extinction coef
You can determine a rough extinction coefficient of your protein
by using the known extinction coefficients of Tyrosine, Cystein, and
Tryptophan at 280nm to give you a molar coefficient.  Use 1300 for Tyrosine, 120
for Cystein and 5700 for Tryptophan.  These numbers
give you a close value (5-10%) of the Molar Absorbance.  Once you 
have the Molar Absorbance, divide that my the MW to get an extinction
Coefficient for a 1.0mg/ml sample, assuming A=elc.

A reference which I have used is found in Analytical Biochem 182, 
319-326 (1989)...Calculation of Protein Extinction Coefficients
from Amino Acid Sequence Data.  By Stanley C. Gill and Peter H.
von Hippel.

Hope this helps.

R. Spencer FIsk

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