At BeijingSBS Genetech, peptide library is usually supplied as either desalt or >70%, >80%, >90%, and >95% purities). Peptides can be made in required amounts from minimal to mg scale for initial screening. Appropriate peptide labels (Biotin, FITC, etc.) can be added upon request. Each peptide in the library undergoes rigorous quality control to avoid any cross contaminants before delivery. All purified peptides are delivered with complete QC data including RP-HPLC, MS, and COA report to ensure high quality. The desalted peptides are provided with MS only. Peptide length in a given library is usually 5-15 aa with 1-5 amino acid overlap.
Peptide library types
Depending upon a given application, peptide libraries are usually defined as:
A. Overlapping Peptide Library
Overlapping peptide library can be used for epitope mapping. The peptide length (5-15aa) and offset number or the degree of overlapping amino acids (2-5 aa) is determined by the length of the full length proteins, overall experiment objectives and the cost. As a general guideline, shorter peptides have less chance for multiple epitope hits. Greater degree of overlapping (small offset number) gives more chances of multiple epitope hits.
Example: (peptide length 10 aa, offset/overlap 3 aa)
Total peptides, n=11
B. Alanine Scanning Library
Example: (peptide length 10 aa)
C. Truncation Library
Truncated peptide library can be used to identify the shortest amino acid sequence needed for a given function or activity.
Example: (peptide length 10 aa) Truncation from the N-terminus
Truncated peptides can also be generated from the C-Terminus.
D. Random/scrambled Library
Scramble Library is constructed by carrying out permutation on the original peptide’s sequence. The number of each amino acid (e.g. 2 Arg or R) is the same in the peptide except its position and other amino acids are created at random. This strategy is used for preliminary identification of a group of active sequences that may possess a given function or activity.
E. Positional Scanning Library
A selected position or positions in a peptide sequence are each systematically replaced with all other natural amino acids (20) or any other amino acid to determine the preferred amino acid residues at a given position that will maximize the peptide activity.
Example: peptide length 10 aa, with substitution of “K at position 5.
Potential peptides =20 with all 20 natural amino acids. It is also possible to study the replacement of “N” at position #8.
Peptide Library Pricing
Peptide libraries are synthesized on SBS Genetech’s unique proprietary synthesis platform and are typically supplied at the 2-4 mg scale for fast, efficient screening work.
Peptide library pricing (per peptide) for up to 15 amino acids.
- Desalted peptides are provided with MS only.
- Purified peptides are provided with MS and HPLC data.