BOC Sciences provides custom peptide library synthesis for research teams that need well-designed, screening-ready peptide sets rather than isolated sequences. Our support covers library strategy, sequence generation, parallel synthesis, sequence-specific troubleshooting, purification, analytical review, pooling, plate formatting, and hit resynthesis. Projects can be configured for epitope mapping, peptide lead optimization, protein interaction studies, enzyme profiling, immunology research, and other high-throughput screening applications.
Peptide library synthesis is the planned preparation of a collection of related peptide sequences in which length, overlap, residue substitutions, truncation pattern, sequence diversity, cyclization, or functional modifications are systematically controlled. Unlike one-off peptide synthesis, a library must be designed as a complete experimental set: each member should answer a defined screening question, remain traceable to its sequence and position, and be delivered in a format compatible with the intended assay. Effective library design therefore connects sequence space, synthetic feasibility, quality assessment, and downstream screening from the beginning of the project.
Overlapping libraries tile an entire protein sequence with short peptides that advance by a fixed offset, enabling systematic linear epitope mapping and binding-site localization. We synthesize complete overlapping sets in a single parallel campaign, including sequences drawn from long or difficult proteins supported by our long peptide synthesis expertise.
Alanine scanning replaces each residue of a bioactive peptide with alanine one position at a time, revealing which side chains contribute most to binding or activity. The result is a compact, information-dense dataset that feeds directly into SAR interpretation and analog design.
Truncation libraries shorten a peptide stepwise from the N-terminus, the C-terminus, or both, identifying the minimal sequence that retains activity. Removing non-essential residues frequently improves synthetic accessibility, solubility, and cost efficiency for downstream programs.
Scrambled libraries retain the amino acid composition of a parent peptide but reorder its sequence, providing rigorous negative controls. Well-designed scrambled and unrelated control peptides demonstrate that observed activity depends on sequence order rather than composition or charge.
Positional scanning libraries saturate each position of a peptide motif with all proteinogenic amino acids while holding the remaining positions fixed, often delivered as defined mixtures. Screening the mixtures identifies favored residues at every position and deconvolutes efficiently toward individual high-value sequences.
Random and combinatorial libraries explore broad sequence space when no motif is known in advance. Using split-and-pool synthesis and combinatorial design, we build diverse or focused collections whose size matches your screening capacity—from thousands of individual peptides to structured mixture libraries.
Cyclic and conformationally constrained libraries lock peptides into defined shapes that often bind targets more tightly and resist proteolysis. We prepare head-to-tail cyclic, side-chain-to-side-chain, disulfide, and stapled collections using chemistries validated on individual macrocycles.
Modified libraries carry the chemical details that determine biological behavior—phosphorylation, acetylation, methylation, glycosylation, D-residues, or terminal caps—plus functional handles for capture and detection. Building on our modified peptide synthesis experience, we routinely produce libraries that combine sequence diversity with precise, position-specific modification.
BOC Sciences helps research teams turn a protein sequence, a lead peptide, or a screening hypothesis into a well-structured library—covering design, parallel synthesis, per-peptide QC, pooling, plate formatting, and hit resynthesis in one coordinated project.
BOC Sciences integrates library design, parallel peptide synthesis, modification chemistry, purification, and analytical characterization to support peptide libraries with different sequence complexities, screening formats, and research objectives.
BOC Sciences supports peptide library projects from first concept to hit follow-up chemistry, with each category available as a standalone service or as part of an integrated program. Key categories include:
| Project Category | Service Scope & Key Outputs |
| Library Design Consultation | Review of the biological question, target sequence, and assay format; recommendation of library type, peptide length, offset, and coverage; synthesis difficulty assessment; and a costed design that matches library size to screening capacity. |
| Parallel Peptide Synthesis | Multi-channel Fmoc SPPS of complete libraries—overlapping, alanine scanning, truncation, positional scanning, random, cyclic, or modified—with matched scales, synchronized protocols, and MS confirmation for every member. |
| Quality Control & Analysis | Per-peptide mass confirmation, analytical HPLC purity review, optional amino acid analysis, net content and counterion checks, and release documentation structured for quick, sequence-level review. |
| Pooling & Plate Formatting | Design and preparation of peptide pools, including matrix layouts for efficient deconvolution; aliquoting into 96-/384-well plates or tubes; DMSO stock preparation; and complete plate maps with concentration and QC references. |
| Hit Resynthesis & Scale-Up | Resynthesis of confirmed hits as purified single peptides at larger scale with matched QC and counterion control; chemical resynthesis support for analog series; and scale-up to gram quantities for advanced studies. |
| Modified & Special-Format Libraries | Phosphorylated, glycosylated, labeled, cyclic, and D-amino acid libraries; conjugates for immunization and capture prepared with our bioconjugation team; peptide-pool and other special-format projects coordinated case by case. |
Share your target sequence or lead peptide, the biological question, intended assay format, preferred scale and purity, and any modification or labeling requirements. Our specialists will return a structured library design with synthesis difficulty notes, a QC and pooling plan, and a transparent quotation.
BOC Sciences reviews the project goal, target sequence, assay format, and budget with the client, then confirms the library type, peptide length, coverage, scale, purity tier, and delivery format in a written design that doubles as the project baseline.
Our team synthesizes all members in parallel by Fmoc SPPS, applies sequence-specific tactics where difficult regions are predicted, cleaves and precipitates each peptide, and performs initial MS identity checks to catch problems early.
Peptides are purified or desalted according to the agreed tier, counterion-exchanged when required, quantified, pooled or arrayed into plates, and formatted as lyophilized powders or ready-to-use DMSO stocks with complete plate maps.
Clients receive the library together with per-peptide QC data, plate maps, and net weights, followed by resynthesis of confirmed hits at larger scale and analog support that feeds hit identification and downstream optimization programs.
Large libraries inevitably contain sequences with very different synthetic behavior: hydrophobic stretches, aggregation-prone regions, or repeat motifs that couple poorly under standard protocols. When even a handful of members fail, epitope coverage or SAR completeness suffers. BOC Sciences predicts difficult members during design, applies tailored tactics—double coupling, pseudoproline dipeptides, alternative resins—and communicates expected risk before synthesis begins. Failed members are re-attempted under revised conditions rather than silently dropped, keeping library coverage intact.
Full coverage of a long antigen or an exhaustive scanning design can generate more peptides than the screening assay can absorb, while over-trimming risks missing the biological answer entirely. BOC Sciences helps clients size libraries to their real throughput: offset adjustments for overlapping sets, prioritized sub-libraries, pooled screening designs with defined deconvolution paths, and staged synthesis in which a first wave informs the second. This keeps projects affordable without sacrificing the sequence space that matters.
Transmembrane segments, aggregation-prone motifs, and heavily modified sequences—multi-phosphorylated, glycosylated, or D-amino-acid-rich—are the classic weak points of library synthesis. We address these with residue substitution where biology allows, backbone-protection strategies, optimized cleavage and scavenger cocktails, and solvent systems chosen for downstream handling. For modified members, building-block availability and installation chemistry are confirmed at the design stage, not discovered mid-project.
Screening data are only as good as the comparability of the peptides behind them. Variation in net peptide content, residual TFA salts, or purity can distort apparent potency across a library and mislead hit ranking. BOC Sciences synthesizes all members under synchronized protocols, quantifies by net weight and, where needed, amino acid analysis, performs counterion exchange to a uniform form, and documents purity and mass for every member—so rank-ordering in your assay reflects sequence effects rather than sample-preparation artifacts.
Collaborate with BOC Sciences for library design, parallel synthesis, rigorous QC, pooled and plated delivery, and seamless resynthesis of confirmed hits—so your screening campaign starts with chemistry you can trust.
A peptide library project does not end at delivery. BOC Sciences carries confirmed hits forward into resynthesis at higher purity and scale, analog iteration, and hit to lead chemistry support. Working with one team from first design to follow-up avoids re-transferring sequences, QC standards, and project context between suppliers.
From a focused alanine scan of a dozen peptides to proteome-scale overlapping sets of thousands, we adjust library size, per-peptide scale, and purity tier to the assay: crude-with-MS for pooled screens, purified material for quantitative work. Custom libraries outside standard formats are designed and quoted case by case.
Our chemists routinely install phosphorylation, glycosylation, methylation, D-residues, and macrocyclic or stapled constraints across full libraries—not just single examples. Difficult modification chemistry is validated on representative members first, then applied uniformly so every member of a modified library remains directly comparable.
Every peptide is identity-confirmed by MS, with analytical HPLC review, net content, and counterion documentation delivered per member. Our analytical platform supports deeper characterization—HRMS testing, sequencing-grade MS/MS confirmation, amino acid analysis—whenever a project's interpretation demands it.
Client Needs: A biologics research group needed to map the linear epitope of a candidate IgG1 monoclonal antibody on a 210-amino-acid recombinant antigen. They required a complete overlapping series with N-terminal biotin tags for streptavidin-based ELISA screening.
Challenges: The antigen contained two hydrophobic segments where peptide solubility and synthesis yield were expected to fall, and the detection format demanded that biotin be installed cleanly on every member without a spacer long enough to obscure epitope accessibility.
Solution: We designed 50 overlapping 12-mers at an 8-residue offset and synthesized them in parallel by Fmoc SPPS with a compact PEG-biotin handle at the N-terminus. Four low-yield members were rescued with pseudoproline tactics and extended coupling. Every peptide was mass-confirmed, reviewed by analytical HPLC, and delivered as weighed, plate-mapped aliquots with a solubility guide.
Outcome: Screening localized the antibody's binding site to a 14-residue window spanning one hydrophobic segment, giving the team a defined epitope for mutagenesis and specificity engineering.
Client Needs: A microbiology team profiled an 18-residue cationic antimicrobial lead derived from a host-defense protein fragment, aiming to define the minimal active core and identify residues essential for potency before expanding into a second-generation analog series.
Challenges: The Arg/Lys-rich sequence produced strong cation-exchange behavior and difficult purification, and the membrane-integrity assay required uniform peptide quality plus a cell-compatible counterion form across all analogs.
Solution: We synthesized an 18-member alanine scan and a 15-member truncation series in one parallel campaign, applying optimized cleavage scavengers to suppress guanidination side products. All 33 peptides were purified by preparative RP-HPLC, verified by MS, and counterion-exchanged from TFA to acetate so that potency ranking reflected sequence rather than salt form.
Outcome: The scan identified three non-substitutable residues and an 11-mer core retaining full activity at lower synthesis cost, which the team advanced into a second-generation analog program.
Client Needs: An immunology group needed a 15-mer peptide pool spanning a 350-amino-acid tumor-associated antigen for IFN-γ ELISPOT monitoring of donor T-cell responses, with deconvolution-ready pooling and sufficient material for repeat donor panels.
Challenges: The full-coverage design produced 84 peptides that exceeded single-plate assay capacity, and inconsistent solubility across the set risked uneven pool stoichiometry that would bias spot-forming responses.
Solution: We synthesized all 84 overlapping 15-mers (11-residue offset) in parallel, quantified each member, and built a matrix pooling layout in which every peptide appears in exactly two pools for rapid deconvolution. Members were pooled at equimolar ratios, quality-checked by LC-MS sampling, and delivered both as dry sets and ready-to-screen DMSO stocks with complete plate maps.
Outcome: Matrix screening of donor PBMCs resolved activity to two pools and deconvoluted to a single responsive 15-mer, which we resynthesized at higher purity for follow-up clone characterization.
The right library design depends on what you want the screening experiment to reveal. Overlapping libraries are useful for locating active or binding regions across a longer sequence, while alanine scanning helps identify residues that are important for activity or interaction. Truncation libraries can define a minimal active sequence, and positional or combinatorial libraries are better suited to exploring residue preferences around an existing motif. BOC Sciences can evaluate your parent sequence, screening objective, assay capacity, modification needs, and follow-up strategy to build a focused library without unnecessary sequence redundancy.
Peptide length and overlap should be selected according to the biological question rather than using one fixed design for every project. Shorter offsets create greater sequence coverage and finer positional resolution but also increase the total number of library members. Longer peptides may preserve more interaction context, whereas shorter peptides can help narrow an active region more precisely. For T-cell, antibody-binding, protein-interaction, or functional screening projects, BOC Sciences can compare peptide length, offset, terminal coverage, predicted sequence behavior, and plate capacity before generating the final sequence set.
Yes. Hydrophobic, highly charged, aggregation-prone, sterically demanding, or modification-rich peptides can often be incorporated into a library, but they may require sequence-specific synthesis and handling rather than identical conditions across the entire set. BOC Sciences reviews difficult motifs before synthesis and can adjust resin selection, coupling strategy, reaction conditions, solvent environment, cleavage handling, and purification approach for individual members. This sequence-aware strategy is particularly valuable when a library spans membrane-associated regions or contains chemically diverse analogs that behave differently during solid-phase peptide synthesis.
Quality assessment should preserve traceability at the individual peptide level while remaining practical for a large sequence set. BOC Sciences can organize LC-MS, HPLC, or other project-appropriate analytical data by peptide identifier, sequence, modification status, and plate position. Libraries can also be supplied with sequence lists, well maps, pooling records, and analytical summaries so screening results can be linked back to specific members. The depth of characterization can be adjusted according to whether the project involves a broad exploratory screen, a modified library, or a smaller group of confirmed candidates.
Active hits are usually the starting point for a more focused second-generation library rather than the end of the project. A positive peptide can be resynthesized and then expanded into alanine substitutions, N- or C-terminal truncations, positional variants, cyclic analogs, or modified derivatives. These focused sets help determine which residues are essential, which positions tolerate substitution, and whether sequence length or conformation can be changed while retaining the desired response. The resulting structure-activity information can then guide selection of a smaller number of peptide candidates for deeper research.
Their team caught that our first overlapping design doubled coverage in a low-interest region while leaving the binding domain tight. The revised offset cut the library by a third without losing useful sequence, and their difficulty notes on hydrophobic members proved accurate.
— Dr. Flores, Immunology Program Lead
Across roughly 900 peptides we saw remarkably consistent behavior in our screening assay—only a handful of members needed discussion, and each came with clear MS and purity documentation. The uniform DMSO stocks dropped straight into our automation.
— Rivera, Senior Peptide Chemist, Discovery Biology
The delivery package was exactly what our informatics group needed: sequence, net weight, purity, counterion, and plate position consolidated in one map. Importing the library into our LIMS took an afternoon instead of a week.
— Dr. Hernandez, Assay Development Manager
When screening flagged two hits, resynthesis of purified material and an initial analog set followed smoothly from the original project context. Not having to re-explain the design made the follow-up chemistry fast and reliable.
— Jones, Principal Scientist, Peptide Drug Discovery
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