The contribution of the carbohydrate chain (i.e. sialic acids) to the pI of
immunoglobulins is very small compared to what the variable region brings
in. Moreover, the sialic acid content is small and the protein is large,
reason why sialoglycoforms differ only slightly in pI. Thus, separating
immunoglobulins in its glycoforms might work with monoclonal
immunoglobulins, but not with polyclonal.
If you want to isolate immunoglobulin glycoforms, you could try using a
lectin-Sepharose column and purified polyclonal or monoclonal
immunoglobulin.
Maurits Pekelharing
Clinical Biochemist
Reinier de Graaf Hospital,
Delft, the Netherlands.
> > I realise that immunoglobulins are a heterogeneous group of
> > proteins but I am planning to separate out glycoforms of
> > immunoglobulins. The method I intend to use will work best
> > at the pI of the protein under study. Do you know if there
> > is an "average" pI of immunoglobulins ?
> >
> > Craig Webster
> > Senior Clinical Biochemist
> > Nottingham City Hospital
> >
> >
>
> -----------------------------------
> pamela riches
> [log in to unmask]
> St. George's Hospital Medical School
> Opinions expressed those of the author and not the institution
>
>
>
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