Custom Peptide Arrays
Peptides are synthesized as macroarray on cellulose membranes . These cellulose-bound peptides are then dissolved as peptide-cellulose conjugates and transferred in a large number of copies onto microarray glass slides .
Peptides are synthesized as macroarray on cellulose membranes . These cellulose-bound peptides are then dissolved as peptide-cellulose conjugates and transferred in a large number of copies onto microarray glass slides .
Peptide arrays on microarrays is possible to screen a high number of peptides . However, due to the minuscule amounts of peptides synthesized directly on chips, and because of interactions of the peptides with the chip surface, this approach has proven to be difficult and often unreliable. These disadvantages can be overcome using peptide macroarrays on cellulose membranes. These are useful for solid-phase screening as well as solution-phase assays. Cellulose membranes are porous, hydrophilic, flexible and stable in organic as well as aqueous solvents. These properties make cellulose paper very useful for biochemical and biological studies in aqueous as well as in organic media and are a major reason why cellulose is still the most widely used material for macroarray membranes.
Depending on the purpose of the screening, different array formats can be generated. The standard size of the spots containing peptides is between 1 and 2 mm in diameter (small spots). For solution assays, we synthesize the peptides in spot with a diameter of 5-7 mm (large spots).
Epitope Mapping
Epitope mapping is a very useful method for screening a known protein sequence for biologically active regions (e.g. epitopes for antibody binding).
Substitution Analysis
Substitution analyses are used for investigation of the importance of amino acids and their possible exchanges in a known peptide sequence.
Truncation Analysis
To investigate the minimum possible length of an active peptide while maintaining activity, variations of the peptide sequence are synthesized by systematic shortening by one amino acid residue at each step from the C-terminus, N-terminus, and both termini simultaneously. The number of peptides on the array is dependent on the starting length of the parent (wild-type) peptide.
Random Peptide Library - CPAP4
To screen for active peptides without prior knowledge of a starting sequence, a random peptide library can be used. Advantage of the random peptide array is that the peptides on each spot are unique, providing the possibility of higher individual activity.
Combinatorial Peptide Library
A very powerful method for screening active peptides without knowing the actual sequence is the combinatorial peptide library. Using combinatorial libraries, screening begins in theory with the entire pool of possible peptide sequences.
Cluster Peptide Library
To reduce the number of possibilities, combine several amino acids of similar properties in clusters (e.g. hydrophobicity – Ile, Leu, Val; or steric similarity – Ser, Cys, Abu). These cluster amino acid peptide libraries provide easier and faster screening of large peptide libraries. It is a very useful alternative screening method to combinatorial and random peptide libraries. It is of course necessary to resolve these clusters at the end of the screening process.