using UV absorbance scans to 'measure' homogeneity of pr

tob at ssi.dk tob at ssi.dk
Mon Sep 6 02:52:49 EST 1999


The UV absorbance (250-280 nm) of a protein is dependent on the proportion of the cyclic amino acids tryptophan, tyrosin and phenylalanin in the protein. A pure preparation of a protein therefore has a distinct UV profile. Compare for example the absorbance of protein A, albumin and IgG. 

The absorbance differences are, most of the times, not large enough to measure any protein homogeneity. For example, for a large protein, containing many of all three cyclic amino acids, the UV absorbance will mostly lookthe same as for a mixture of proteins. 

My guess is that you could only use it for homogeneity purposes if the protein has an unusual ratio of W, Y and F amino acids. For a short theoretical background you could look at Current protocols of protein science, chapter 7.2.

Tomas   
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