Gels Mimicking Antibodies in Their Selective Recognition of Proteins and Its Potential Use for Protein Crystallization - Molecules: Nucleation, Aggregation and Crystallization - page 26

non-specific interaction with proteins (Hjertén et al. , 1987). Since our
working hypothesis on selective recognition is partly based on non-
specific interactions, an agarose gel was prepared in the presence of hemo-
globin and at the same time cross-linked with divinyl sulfone (Hjertén et al .,
1987). This gel showed specific adsorption of hemoglobin although the
loading capacity was low. It should be stressed that cross-linking of agarose
only slightly affects the pore size of the gel (Porath et al ., 1975).
Artificial gel antibodies for detection of biomarkers
The high selectivity of the gel antibodies can be used to “fish out” a bio-
marker from a body fluid for diagnosis and prognosis of a particular disease
(Ghasemzadeh et al. , 2008a; 2008b). From a standard curve one can then
rapidly determine the concentration of the biomarker in, for instance, serum
or cerebrospinal fluid (CSF).
For the design of the standard curve CBB (Coomassie Brilliant Blue),
staining of proteins selectively adsorbed to the artificial gel antibodies has
the great advantage that it absorbs light at 588 nm, where the light scat-
tering from polyacrylamide gel granules is negligible (Fig. 7). The meas-
ured adsorption value of the biomarker (the protein selectively adsorbed
to the gel granules) inserted into the calibration curve (Fig. 7) gives on the
x -axis the concentration of the biomarker in the sample solution.
We applied this method to estimate the concentration of albumin in
plasma and CSF samples from patients with amyotrophic lateral sclerosis
(ALS). Difficulties in detection and treatment of diseases together with a
lack of suitable diagnostic and prognostic tools have indicated a need for
discovery or identification of relevant proteins or peptides which can
serve as biomarkers for a disease. An example is given in Fig. 8, which
shows that albumin in cerebrospinal fluid is a biomarker for neurological
diseases such as ALS.
The mean levels of albumin in CSF from ALS patients were more
than twice as high as in the control subject (Fig. 8(a)). This finding is in
agreement with results from earlier studies, which confirms the validity
of our analysis technique and suggests that the barrier permeability for