BOC Sciences provides expert stapled peptide synthesis services based on proven solid-phase and solution-phase methods. Our team handles sequence design, non-natural amino acid incorporation, macrocyclization by RCM, lactam formation, click chemistry, and disulfide or thioether bridging, followed by purification and multi-method characterization to support protein-protein interaction research, oncology programs, and anti-infective peptide development.
Stapled peptide synthesis is the chemical construction of peptides in which two amino acid side chains are covalently linked to form an intrahelical macrocyclic bridge. This crosslink, or staple, constrains the peptide in an alpha-helical conformation, improving proteolytic stability, membrane permeability, and binding affinity toward intracellular protein targets. Stapling chemistries include all-hydrocarbon bridges formed by ring-closing metathesis, lactam bridges between Asp/Lys or Glu/Lys pairs, disulfide bonds, 1,2,3-triazole linkages via click chemistry, and thioether bonds. These constructs are widely used to mimic endogenous helical motifs that mediate protein-protein interactions.
Our stapled peptide services combine oligopeptide synthesis, orthogonal amino acid protection, selective macrocyclization, and analytical confirmation. We can prepare one defined construct or a focused panel that compares staple position, spacing, chemistry, or number.
We introduce olefin-bearing amino acids during solid-phase assembly and form an all-hydrocarbon crosslink through ring-closing metathesis.
BOC Sciences prepares side-chain lactam bridges by coupling appropriately positioned acidic and basic amino acid residues.
We generate cysteine-based disulfide staples under controlled oxidative conditions for peptides requiring a reversible, redox-responsive constraint.
Triazole staples are formed from azide- and alkyne-bearing residues to provide a chemically robust linkage with adjustable geometry.
We construct nonreducible thioether bridges through selective cysteine alkylation or related sulfur-based crosslinking strategies.
BOC Sciences prepares longer or structurally complex peptides containing two planned crosslinks for extended conformational control.
Share the sequence, proposed binding region, desired staple chemistry, known solubility issues, and downstream assay. Our scientists can compare feasible anchor positions and develop a synthesis and characterization plan.
The staple must be considered together with the peptide sequence and intended target. BOC Sciences offers flexible design variables that allow clients to compare structurally meaningful candidates rather than relying on a single fixed construct.
| Design Variable | Available Options | Purpose |
| Staple Chemistry | Hydrocarbon, lactam, disulfide, triazole, thioether, or compatible dual-staple designs. | Compare bridge stability, polarity, geometry, synthetic accessibility, and compatibility with the downstream experiment. |
| Staple Position | Common i, i+4 and i, i+7 placements, alternative spacing, and several position variants. | Place the constraint away from key binding residues while testing its effect on helicity, solubility, and activity. |
| Staple Number | Single-stapled, double-stapled, stitched, or linear comparator peptides where chemically feasible. | Adjust the length and degree of conformational restriction while preserving a meaningful control set. |
| Terminal Design | Free amine or acid, N-terminal acetylation, C-terminal amidation, and terminal functional handles. | Modify charge, stability, conjugation readiness, or compatibility with the intended analytical method. |
| Additional Modification | PEG units, fatty acids, dyes, affinity tags, isotopes, phosphoresidues, noncanonical amino acids, and compatible bioconjugates. | Support detection, pull-down, imaging, property tuning, or application-specific assay development. |
| Control Peptides | Linear parent, unstapled anchor-containing analog, scrambled peptide, point mutant, or alternate-position staple. | Separate staple-related effects from sequence-specific binding and nonspecific physicochemical behavior. |
Provide the parent sequence, target protein or interaction site, preferred staple type, available structural information, required controls, scale, and analytical needs. We can propose a focused set of anchor positions and macrocyclic peptide synthesis routes for feasibility review.
Our team reviews the target peptide sequence, native helical region, proposed staple positions, and non-natural amino acid requirements. We evaluate synthetic accessibility, potential aggregation hotspots, solubility concerns, and compatibility with the requested cyclization chemistry, then deliver a feasibility report with recommended route adjustments.
Based on sequence analysis, we select the optimal staple chemistry, bridge geometry, and non-natural amino acid pairings. Our scientists perform SPPS with appropriately protected building blocks, execute the macrocyclization step under rigorously controlled conditions, and monitor conversion by on-resin or solution-phase analytical checks.
The stapled peptide is purified by preparative RP-HPLC with method optimization for cyclic product resolution. We confirm identity and purity by LC-MS or HRMS, assess helical content by CD spectroscopy, and check monomeric status by SEC. Additional tests including NMR, binding assays, and cell permeability studies are available on request.
Clients receive the purified stapled peptide together with a complete project report covering synthesis conditions, mass spectrometry data, HPLC purity traces, CD spectra, and a summary of any process observations. All records are organized for direct integration into research notebooks, publications, and follow-on project planning.
Hydrophobic sequences rich in aromatic residues or bearing multiple non-natural amino acids often couple poorly during SPPS and aggregate on the resin, leading to truncated sequences and low crude purity. BOC Sciences addresses this by evaluating pseudoproline dipeptides, Dmb-protected glycine derivatives, and segmented condensation strategies. We optimize coupling reagents, resin loading, solvent composition, and temperature to improve stepwise yield and reduce on-resin folding. Analytical monitoring of cleaved aliquots at intermediate stages guides real-time process adjustments.
Ring-closing metathesis and other macrocyclization reactions can stall when olefin handles are sterically hindered, catalyst access is restricted, or competing side reactions deactivate reactive groups. BOC Sciences screens catalyst generations, reaction concentration, solvent mixtures, and temperature profiles to maximize cyclization conversion. For difficult sequences, we evaluate alternative staple chemistries, adjust the spacing between bridge residues, or switch from on-resin to solution-phase cyclization to improve conformational flexibility and ring-closure kinetics.
Stapled peptides often display increased hydrophobicity due to the crosslink itself and the non-natural amino acids required for bridge formation, causing precipitation in aqueous buffers and complicating purification and assay preparation. BOC Sciences mitigates solubility issues by introducing arginine or lysine solubilizing tags, employing PEG-based spacers, adjusting the staple position to surface-exposed helical faces, and optimizing the purification gradient. We also evaluate cosolvent compatibility and provide formulation recommendations for downstream handling.
An improperly placed staple can occlude the binding face, alter side-chain orientation critical for target recognition, or introduce excessive rigidity that prevents adaptive fit at the protein interface. BOC Sciences uses helical wheel projections and structural modeling to position staples on the solvent-exposed helical face while preserving hot-spot residues. We prepare positional isomers when needed and coordinate activity evaluation with the client's binding or functional assays to correlate staple geometry with biological response.
Work with BOC Sciences to connect sequence design, staple chemistry, difficult-peptide synthesis, selective ring closure, purification, structural characterization, and functional comparison in one project workflow.
BOC Sciences supports hydrocarbon, lactam, disulfide, triazole, thioether, and double-stapling approaches. This breadth allows the bridge to be selected according to the peptide's sequence, desired geometry, redox environment, polarity, modification pattern, and downstream assay rather than forcing every target into a single hydrocarbon-stapling workflow.
Each project begins with the actual peptide sequence and target interaction. Our scientists consider anchor stereochemistry, residue spacing, aggregation risk, reactive side chains, binding-face preservation, protecting-group compatibility, and possible purification difficulties. Small-scale route comparisons can be used to resolve uncertainty before additional material or a larger analog set is prepared.
Peptide assembly, stapling, purification, and analysis are coordinated within one development plan. Analytical HPLC and mass spectrometry support identity and purity assessment, while circular dichroism, stability, binding, or activity studies can provide context for candidate selection. This integration is especially useful when the most highly helical or cleanly synthesized analog is not necessarily the best-performing one.
We support exploratory analog panels, defined research batches, control peptides, and compatible terminal or side-chain modifications. Projects may include labels, affinity handles, PEG units, lipids, noncanonical residues, or peptide bioconjugation when the added functionality can be incorporated without interfering with staple formation or the intended binding surface.
Client Needs: A cancer biology group required a hydrocarbon-stapled peptide mimicking the p53 transactivation domain alpha-helix to disrupt the p53-MDM2 interaction in their cell-based target validation assays. They had attempted in-house synthesis but encountered low RCM conversion and significant on-resin deletion sequences.
Challenges: The sequence contained four consecutive hydrophobic residues that caused on-resin aggregation during chain elongation. The initial RCM conditions using first-generation Grubbs catalyst in DCM gave less than 30% conversion, and extended reaction times led to olefin isomerization side products.
Solution: We introduced pseudoproline dipeptides at two positions to disrupt beta-sheet aggregation during SPPS, then switched to a second-generation Hoveyda-Grubbs catalyst in 1,2-dichloroethane at elevated dilution. Eight RCM conditions were screened across catalyst loading, temperature, and reaction time. The optimized protocol achieved greater than 85% cyclization conversion. The stapled peptide was purified by preparative C4 RP-HPLC and confirmed by LC-MS and CD spectroscopy showing characteristic double minima at 208 nm and 222 nm.
Outcome: The client received 45 mg of purified hydrocarbon-stapled peptide at greater than 95% purity with complete analytical documentation, enabling resumption of their target validation program.
Client Needs: A structural biology team needed a double-stapled antimicrobial peptide with two independent hydrocarbon bridges to increase helical stability and protease resistance for mechanism-of-action studies against Gram-positive bacterial membranes.
Challenges: The 28-residue sequence was highly amphipathic and prone to both on-resin aggregation and intermolecular association after purification. The two RCM sites required orthogonal spacing (i/i+4 and i+4/i+8) with different olefinic amino acids, and the second cyclization had to proceed without disrupting the first bridge.
Solution: We designed a sequential cyclization route using two different olefinic amino acid pairs with differential reactivity profiles. The first RCM was performed on-resin under mild conditions to establish the proximal bridge, followed by second-site cyclization in solution phase after resin cleavage. Fourteen conditions were evaluated for the second cyclization step. Purification employed a two-stage RP-HPLC protocol on C4 and C8 columns to resolve the double-stapled product from single-stapled intermediates and linear precursor. Final characterization included LC-HRMS, CD spectroscopy, and analytical SEC confirming monomeric status.
Outcome: The team obtained a well-characterized double-stapled peptide with enhanced alpha-helical content and improved stability in serum, supporting their antimicrobial mechanism research with a reliable tool compound.
Clients should provide the complete peptide sequence, target protein or interaction interface, preferred stapling chemistry, proposed staple positions, required scale, purity specification, and any additional modifications. Available structural models, known binding residues, data for the linear parent peptide, and details of previous synthesis problems are also helpful. BOC Sciences uses this information to assess hydrophobicity, aggregation risk, anchor spacing, protecting-group compatibility, and ring-closure feasibility. We can then recommend suitable stapled candidates and relevant linear, position-variant, or anchor-containing controls.
BOC Sciences supports hydrocarbon, lactam, disulfide, triazole, thioether, and double-stapled peptide synthesis. These approaches differ in bridge structure, polarity, redox stability, required anchor residues, cyclization conditions, and sequence compatibility. The appropriate method is selected according to the peptide sequence, desired conformation, essential binding residues, solubility profile, additional modifications, and downstream research requirements. When one design cannot be selected confidently, we can prepare a focused panel comparing different staple chemistries, positions, or linker geometries to support experimental evaluation.
Staple placement is guided by the predicted or experimentally determined α-helical structure, target-binding interface, essential functional residues, and selected cyclization chemistry. Common hydrocarbon-stapling arrangements include i, i+4 and i, i+7 spacing, although these patterns are not appropriate for every sequence. BOC Sciences evaluates anchor stereochemistry, tether length, terminal proximity, hydrophobicity, and aggregation risk while avoiding replacement of important binding residues. For projects without sufficient structural information, several position variants can be synthesized and compared with the linear parent peptide.
Yes. Double-stapled peptides may incorporate terminal capping, lipidation, PEGylation, phosphorylation, fluorescent labels, stable isotopes, affinity handles, or other noncanonical amino acids when the sequence and route are compatible. Project design must account for orthogonality among the two ring-closure reactions, additional modification steps, and protecting groups to prevent site interference, partial cyclization, or difficult purification. BOC Sciences can establish the assembly and closure sequence first, then introduce suitable modifications and prepare matched single-stapled or unstapled controls for comparative structural, stability, and activity studies.
Routine characterization generally includes analytical RP-HPLC and LC-MS to assess chromatographic purity, molecular mass, and major product-related impurities. High-resolution MS, amino acid analysis, and circular dichroism spectroscopy can be added to examine identity, composition, and secondary structure. Selected projects may also include NMR studies, solubility assessment, aggregation evaluation, protease or serum stability testing, binding-affinity measurements, and application-specific activity assays. Results are interpreted alongside the linear parent or other controls because increased helicity alone does not necessarily produce improved target binding, cellular uptake, or biological activity.
The team did more than follow our initial sequence request. They reviewed the proposed binding face, identified a potentially disruptive staple position, and suggested a focused set of alternatives and controls. The resulting design panel gave us a much clearer basis for comparing structure and binding.
— Dr. O'Connor, Peptide Research Scientist
Our hydrophobic sequence had failed in an earlier synthesis attempt. BOC Sciences explained where aggregation was occurring, adjusted the assembly and purification strategy, and kept us informed as the route developed. The final sample and analytical package were straightforward to evaluate.
— Dupont, Project Manager, Peptide Discovery
We appreciated receiving the stapled candidate together with well-selected control peptides. The HPLC, mass, and circular dichroism results were organized clearly, and the comparison helped us distinguish improved structural stability from changes in binding behavior.
— Dr. Bradley, Senior Scientist, Biophysical Research
The double-stapled peptide required several adjustments, but the project remained easy to follow. We received concise updates on assembly, ring closure, purification, and analytical findings, along with practical recommendations for handling the final hydrophobic peptide in our downstream assays.
— Cunningham, Research Director, Anti-Infective Discovery
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