Custom peptide synthesis
Custom Synthesis
Contract synthesis for formulators, diagnostic developers and research groups.
01 / Scope
What a custom programme has to define.
A quotation is only meaningful once these fields are fixed. Each one changes yield, purification strategy and price.
| Field | What we need from you | Why it matters |
|---|---|---|
| Sequence | Single-letter code or FASTA; non-standard residues marked | Drives coupling strategy and the mass you should expect |
| Length | Residue count, plus any difficult stretches | Long or hydrophobic stretches need segment coupling |
| Modifications | Type and exact position | Determines whether the group is added on-resin or in solution |
| Purity target | Grade and the method used to measure it | “95 %” is not comparable across methods |
| Counter-ion | Acetate, TFA or chloride | Affects solubility, cell tolerance and peptide content by mass |
| Quantity | Mass per lot, number of lots, schedule | Sets batch size and whether a scale-up run is required |
| Format | Bulk, pre-weighed vials, plates, solution | Changes filling, packaging and stability data |
| End use | Cosmetic, food, diagnostic, research | Sets the quality and regulatory route for the lot |
Programme limits — routine length [PLACEHOLDER: residue range], scale per lot [PLACEHOLDER: mg – g], quotation in [PLACEHOLDER: working days]. Values are confirmed in the written quotation.
02 / Process
Five stages, each with a document you keep.
You should always know which stage a project is at and what has been signed off.
Sequence review and quotation
We check for aggregation-prone stretches, difficult couplings and modification feasibility, then quote against a written specification. Every assumption is listed.
Solid-phase synthesis
Stepwise SPPS with monitored couplings. Difficult sequences may need double coupling, pseudoproline dipeptides or a different resin — all recorded.
Cleavage and purification
Cleavage cocktail matched to the residue composition, then preparative RP-HPLC with fraction analysis by analytical HPLC and MS.
Analytics and release
Purity by RP-HPLC at the agreed wavelength, identity by LC-MS, plus water content and counter-ion where specified. Released only against the signed specification.
Packing and documentation
Packaging chosen for hygroscopicity, labelled with batch number and storage condition, shipped with COA, TDS and SDS.
03 / Modifications
Chemistry that changes how the peptide behaves.
Most requests are about a terminal group, a label or a constraint — not a new sequence.
| Modification | Notation | Typical purpose | Point to watch |
|---|---|---|---|
| N-terminal acetylation | Ac- | Blocks aminopeptidase attack; removes the terminal charge | Shifts the expected mass by +42 Da |
| C-terminal amidation | -NH2 | Matches naturally amidated peptides; improves stability | Requires the right linker; −1 Da versus the acid |
| Acylation / lipidation | Pal-, Lau-, Myr- | Membrane anchoring; skin penetration in cosmetic actives | Hydrophobic peptides need different gradients |
| Biotinylation | Biotin- | Streptavidin capture, ELISA, pull-down | Spacer length affects binding access |
| Fluorescent labelling | FITC, 5-FAM, Cy5 | Imaging, binding assays, tracers | Label at the terminus outside the binding site |
| Phosphorylation | pSer, pThr, pTyr | Signalling research, phospho-specific antibodies | Phospho-esters are labile |
| Disulfide cyclisation | Cys(Acm) / free Cys | Conformational constraint, receptor selectivity | Multiple cysteines need a defined scheme |
| Head-to-tail cyclisation | cyclo(-) | Proteolytic stability, rigid scaffold | Efficiency falls with ring size |
| Stable isotope labelling | 13C / 15N | MS quantification, internal standards | Isotopic purity is specified separately |
| FRET dye–quencher pairs | Edans/Dabcyl, FAM/BHQ | Protease substrate assays | Both labels must be quoted as one product |
| Carrier conjugation | KLH, BSA, OVA | Immunogen preparation | Conjugation ratio belongs on the COA |
Modifications not listed are quoted individually. [PLACEHOLDER: list of in-house validated modifications]
04 / Peptide libraries
Screening sets, built so results are comparable.
A library is only useful if every member is made the same way: one resin lot, one cleavage, one analytical method.
| Library type | How it is built | Typical use | QC |
|---|---|---|---|
| Overlapping peptides | Walk-through of a parent sequence with a fixed window | Epitope mapping, T-cell assays | Pool and individual MS |
| Alanine scanning | One residue replaced by alanine per member | Finding residues that matter for binding | Individual purity where requested |
| Positional scanning | Each position varied against a fixed scaffold | Motif optimisation | Pool-level identity |
| Random / biased pools | Split-and-mix or parallel synthesis | Hit discovery | Degeneracy confirmed by MS |
| Custom arrays | Individually specified sequences in plate format | Screening against a target panel | Per-well COA on request |
Library size, plate format and per-member quantity are agreed per project: [PLACEHOLDER: library scale range].
05 / What to send
A complete brief saves a quotation round.
Paste this list into your enquiry. An assumption we make silently is the most common cause of a failed first lot.
- Sequence in single-letter code or FASTA, non-standard residues marked
- Modifications with exact positions
- Purity target and the method you will use to check it
- Counter-ion preference
- Mass per lot and number of lots
- Format: bulk, vials, plates or solution
- Documents required, and the language
- End use and destination country
| Sequence | Single-letter code or FASTA |
| Modifications | Type and position, e.g. N-terminal acetyl, Lys-12 biotin |
| Purity | Target grade and test method |
| Counter-ion | Acetate, TFA or chloride |
| Quantity | Mass per lot and number of lots |
| Format | Bulk, vials, plates, solution |
| Documents | COA / TDS / SDS, language |
| End use | Application and destination country |
Next step
Send the sequence and the end use.
We tell you what is realistic before you commit.