Peptides formalin fixation susceptibility

SOME PEPTIDES ARE DIRECTLY SUSCEPTIBLE TO FORMALIN FIXATION... 

To study the role of lysine residues in susceptibility to formalin fixation, the amino acid composition of immunoreactive peptides (to various monoclonal antibodies) was studied. Each peptide was evaluated to determine if immu-noreactivity was lost after formalin fixation. Formalin sensitivity was correlated with the peptides amino acid composition. The first step in the method is biopanning from a peptide combinatorial library with a monoclonal antibody. The peptides that bind to the antibody were tested for their sensitivity to formalin fixation. Some peptides remain immunoreactive whereas others do not. The peptides were then sequenced to look for differences between those that were sensitive to formaldehyde versus those that were not. The goal was to find whether there is a particular amino acid that is present in formalin-sensitive epitopes but absent in formalin-resistant epitopes, or vice versa. An advantage of this approach is that it is open-ended, without excluding any amino acids. 

Figure 16.4 Graph depicting the percentage of lysine residues among peptides that bind to the indicated monoclonal antibodies. The peptides were isolated after affinity selection (biopanning) from a phage-displayed combinatorial peptide library. The peptides are grouped as to whether they are susceptible to formalin fixation, resulting in a loss of immunoreactivity.

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