Basic HTML Version
83
cells, or that the polymers are partially and randomly degraded during
isolation and purification. The polydispersity of an alginate and a xanthan
sample is visualized in the figure:
Figure: Electron micrographs of alginate (top) and xanthan (bottom) molecules
absorbed to a mica surface. Bar: 200 nm
In contrast, many peptides proteins are strictly monodisperse. All chains are
then identical. Essentially monodisperse polysaccharides may be obtained by
special fractionation methods.
2.1.5. Molecular weight distributions
An accurate and complete description of the molecular weight - or equivalently
the chain length distribution – would involve assigning the relative amount
(weight fraction or number fraction) of each chain length in the sample. This
can be illustrated in a table
27
and a corresponding bar graph:
27
File: Simple distribution.xlsx