Removal of protein from glycogen extractant?

Dr Engelbert Buxbaum engelbert_buxbaum at
Thu Mar 16 10:49:35 EST 2006

Ngo Thi Thuy Huong wrote:

> Dear all,
> I am doing glycogen quantification in biological
> materials and I faced a problem which I tried to solve
> for 2 weeks now but I did not get much better. I tried
> to establish a standard curve from mussel glycogen
> standard but the standard deviation are always very
> very high, r-square are about 0.95 - 0.97. In
> literature I found that it might be cause by the
> interfernce of protein. Then I tried to remove protein
> from the samples by two methods:

Are you sure it is not simply your pipetting? No offence intended, but
it takes months of practice until one can reliably pipet to a standard
deviation of 2% or less. And your r^2 can easily happen if you only have
a few data points. 

If you have always the same protein composition and protein/glycogen
ratio, the presence of protein should not increase standard deviation
(although it may affect the correctness of the result), unless the assay
design is faulty (e.g. protein precipitates are not removed before
photometric reading). Can you tell us which method you are using?

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