Custom peptide modifications, fluorescent labeling, biotinylation and conjugation for research. Specify modification sites, purity and quantity for a quote.
Alan Scientific offers custom peptide modifications for labeling, affinity capture, enzyme assays, structural studies and peptide analog research. Options include terminal modifications, fluorescent labels, biotinylation, phosphorylation, cyclization, specialty residues and carrier-protein conjugation.
Send your sequence and intended application for review. Modification feasibility, purification requirements and analytical specifications are assessed together before synthesis.
Request a Quote · Email your sequence to sales@alanscientific.com
Start with the measurement or molecular feature your experiment requires. The modification name, attachment site and final peptide structure should be specified together.
| Research Goal | Modification Options | Key Project Inputs |
|---|---|---|
| Fluorescence detection and peptide tracking | FITC, 5-FAM, Dansyl and other labels evaluated on request | Dye, labeling position, linker preference and detection conditions |
| Affinity capture and immobilization | N-terminal or side-chain biotinylation, with or without a spacer | Biotin attachment site, spacer requirements and assay format |
| Enzyme substrate studies | Fluorescent or chromogenic reporters; fluorophore–quencher designs | Substrate sequence, cleavage site, reporter, quencher if applicable and assay readout |
| Modification-dependent recognition | Phosphoserine, phosphothreonine and phosphotyrosine | Modified residue positions and corresponding unmodified controls |
| Conformational and stereochemical studies | Cyclization, D-amino acids, non-natural residues and N-methylation | Residue identities, positions, stereochemistry and intended connectivity |
| Antibody development and characterization | KLH or BSA conjugation | Peptide sequence, carrier, conjugation site and intended immunogen or assay use |
| Mass-spectrometric research | Stable isotope-labeled residues | Residue positions, isotope composition and quantitative documentation requirements |
| Membrane-association and lipidated peptide research | Lipid and fatty-acid modifications | Lipid identity, attachment site, linker and intended assay conditions |
Share the details you already have. If a label, attachment site or other specification is undecided, describe your research objective and identify the choices that still need review.
Terminal options include N-terminal acetylation, formylation and C-terminal amidation. Specify whether each terminus should remain free or carry a defined modification.
Terminal capping changes the chemical identity of the peptide and may affect charge, recognition and degradation behavior. Select the terminal state that matches the molecule being studied; capping does not guarantee improved performance.
For help choosing between free and capped termini, see N-terminal acetylation versus C-terminal amidation.
Fluorescent peptide projects should define both the dye and its attachment position. A label at the N-terminus and the same label on a lysine side chain produce different molecular structures.
Include your detection settings, any required linker and regions that must remain unmodified. Our guide to N-terminal versus lysine side-chain fluorescent labeling explains considerations for selecting a site.
For enzyme substrates, distinguish a fluorescent reporter such as AMC from a chromogenic reporter such as pNA. Fluorophore–quencher designs also require the reporter pair, attachment positions and intended cleavage site to be specified.
Biotinylated peptides can be prepared for capture, detection and immobilization workflows. Specify N-terminal or side-chain attachment and whether a spacer is required.
For KLH or BSA conjugates, identify the carrier, intended application and proposed conjugation site. State whether you also need a separate unconjugated peptide for screening or control experiments. Any added residue used for attachment should be included explicitly in the requested sequence.
Phosphorylated peptides can incorporate phosphoserine, phosphothreonine or phosphotyrosine at defined positions. Identify every modified residue, including its sequence number, and specify whether a corresponding unmodified peptide is required.
For other post-translational modification requests, provide the exact chemical modification and position for feasibility review. A description such as “acetylated peptide” should distinguish terminal acetylation from modification of a residue side chain.
Peptide cyclization and stapling introduce defined constraints for studying conformation, molecular recognition and proteolytic stability. The linkage chemistry and attachment positions should be specified alongside the peptide sequence.
Disulfide cyclization: Connects two cysteine side chains through an S–S bond. Identify the intended cysteine pair for each bridge, especially in sequences containing multiple cysteines, and note any cysteines that must remain free.
Head-to-tail cyclization: Joins the N-terminal amino group to the C-terminal carboxyl group through an amide bond, creating a cyclic backbone without free termini. Specify any additional labels or side-chain modifications that must be incorporated.
Side-chain cyclization: Connects selected side-chain functional groups, for example through a lactam linkage between Lys and Asp or Glu. Indicate the residues to be connected and whether the peptide termini should remain free or be capped.
Stapled peptides: Introduce a covalent bridge between selected residues to constrain a region of the peptide. Hydrocarbon staples commonly use specially configured non-natural residues at positions such as i, i+4 or i, i+7 in designs targeting helical conformations. Provide the staple positions, residue stereochemistry and linker chemistry, or an annotated structure for feasibility review.
Cyclization and labeling should be planned together when they involve the same functional groups. Review peptide cyclization strategies for background on linkage selection and structural considerations.
Individual D-residues, all-D sequences, non-natural amino acids and N-methylated residues provide options for stereochemical and structure–activity studies.
Specify each residue’s identity, position and configuration. For N-methylation, distinguish backbone nitrogen modification from side-chain methylation. Effects on conformation, stability or biological activity must be evaluated in the resulting peptide.
Stable isotope labeling requests should identify the labeled residues and isotope composition. If the peptide will be used quantitatively, include the required content determination and documentation.
For lipidation or other functional groups, provide the chemical identity, attachment site and linker structure. Requests involving multiple modifications are reviewed for compatibility with synthesis, purification and the intended final structure.
Use an N-to-C sequence and number residues from the first amino acid in that sequence. If you also use parent-protein numbering, provide the correspondence.
| Incomplete Request | Information to Add |
|---|---|
| “Biotinylated peptide” | N-terminal or specific side-chain attachment; spacer identity if required |
| “Fluorescent peptide” | Exact dye, attachment position and linker |
| “Phosphorylated peptide” | Residue identity, position and number of phosphorylation sites |
| “Cyclic peptide” | Cyclization chemistry and the groups or residues being connected |
| “D-amino-acid peptide” | Individual D-residue positions or an explicit all-D designation |
For complex structures, attach an annotated sequence or structure drawing. Identify groups that must remain free for your assay or a later conjugation step.
When comparing modified and unmodified peptides, define the control sequences at the same time. Projects involving multiple positions, substitutions or control sequences can be evaluated through our synthetic peptide library service.
Choose purity according to assay sensitivity and the purpose of the experiment. Our recommended peptide purity guide provides a starting point for discussing specifications.
State the quantity required per peptide, along with any requested vial configuration. If your experiment requires a defined amount of target peptide for quantitative work, include the content or concentration requirements in the inquiry.
Analytical HPLC assesses chromatographic purity, while mass spectrometry supports comparison with the expected molecular mass. Molecular mass alone does not establish every modification site or linkage arrangement. Discuss any additional structural or quantitative evidence your project requires before synthesis.
See our peptide quality control reports and analytical options for available documentation and project-specific testing.
Yes, combined modifications can be submitted for review. Provide every modification and its position so that shared attachment sites, protecting-group requirements and purification constraints can be assessed together.
Yes. Send the sequence, intended assay and any regions that must remain unmodified. Include your preferred label if known, and identify which design decisions are still open.
This cannot be assumed. Labels, terminal changes and structural modifications can affect recognition and other peptide properties. Include an appropriate unmodified or alternative-site control when required by your experimental design.
Sequence complexity, modification chemistry, reagent availability, quantity, purification and analytical requirements all contribute. The quotation should reflect the complete requested structure and agreed delivery specifications.
Send your sequence and project requirements through our inquiry form or by email. Include:
Peptide sequence and a name or identifier for each requested peptide.
Modification names, positions, linkers and terminal states.
Intended application and any relevant assay constraints.
Required quantity per peptide and target purity.
Control peptides, salt preferences and additional analytical requirements.
Requested delivery date and any specifications still to be determined.
Modified peptide projects are evaluated within our custom peptide synthesis service, allowing sequence, modification, purification and QC requirements to be considered together.
Prefer email? Send your project details to sales@alanscientific.com