Peptide Amino Acid Bioconjugation

Peptide Amino Acid Modifications and Bioconjugations

Bio-Synthesis provides a one-stop solution for all of your peptide-macromolecule bioconjugation needs. Our custom peptide synthesis, modification, and conjugation services involve chemical modification of peptide at highly specific sites. This allows for the elegant attachment of labels such as fluorescent, chemilluminescent, or chromogenic enzyme substrates. Applications include surface immobilized probes to facilitate diagnostic detection or as drug delivery agents when the peptide is conjugated with any molecular group that adds useful properties—including radionucleotides, drugs, toxins, enzymes, metal chelates, fluorophores, haptens, and others.

Bio-Synthesis gives you the best quality in peptide bioconjugation chemistry in the industry by implementing our state-of-the art gene synthesis platform and expertise in providing high quality nucleic acid bioconjugation reagents. Peptide synthesis, modifications, and conjugates produced at Bio-Synthesis have substantial purity. Each peptide-biopolymer conjugate is meticulously monitored during synthesis and controlled according to our quality assurance and quality control standards. The final product is identified by mass spectrum, amino acid analysis, and the purity is analyzed by HPLC or appropriate analytical methods. QA (quality assurance) procedures are also followed independently to double guarantee the high quality of every delivered peptide. Bio-Synthesis is complient with TQM (Total Quality Management) system.

Biomolecule Peptide Conjugation Services

Bio-Synthesis is a leader in custom peptide synthesis and bioconjugation services with a high success rate well above the industry standard. We are devoted to delivering affordable peptide-biopolymer hybrid complexes, and offer comprehensive modification and labeling options to be used for life science research, diagnostics, and drug discovery.

Over decades, we have accumulated a continually growing portfolio of peptide modification and conjugation services. If you can't find what you want, contact our National Customer Service Center at 800.227.0627, or contact us online with your detailed project descriptions.

Service Portfolios

  • Peptide-enzyme conjugates for Diagnostic Assay
  • Amino acid-oligo conjugates
  • Peptide-Antibody conjugates for drug therapy
  • Peptide-polyethylenimine (PEI) conjugates for imaging and DNA delivery in vivo
  • Biotin-Peptide labeling for immunoassay
  • Peptide-nanoparticle conjugates
  • Peptide-antibody conjugates for Immunoassay
  • DNA, RNA-Peptide Conjugates to study protein to protein interaction
  • siRNA-peptide conjugates for siRNA delivery
  • BNA-Peptide conjugates for therapeutic drug discovery
  • Peptide-DNA conjugates for gene inhibition study
  • Peptide-quantum dot conjugates for high sensitive detection application
  • Peptide-agarose conjugates for affinity chromatography immobilization
  • Peptide-drug conjugates for drug delivery
  • Peptide-lipid conjugates for cellular uptake
  • Oligonucleotide-bead conjugates for Luminex assay
  • Peptide-glass plate conjugate for microarray detection
  • Peptide photoreactive conjugates for nucleic acid-protein interaction
  • Site-Specific peptide labeling by Staudinger Ligation or Click Chemistry
  • Antisense peptide nucleic acid for improving cellular uptake
  • Peptide-based nucleic acid delivery
  • Peptide-polymer hybrid conjugates for diagnostics and biomedicine

Peptide Biconjugation Service Descriptions


Coupling of preactivated small molecule and biomolecule with chemical reactive groups such as amine, thiol, carboxylate, hydroxyl, aldehyde and ketone, active hydrogen, photo-chemical and cycloaddition reactions, zero-lengthcross-linking, homobifunctional, heterobiofunctional, or multifunctional cross-linking chemistries, dendrimer and dendrons, and cleavable reagent systems.

Some commonly used cross-linking reagents include:

  • glutaraldehyde - links carrier molecules to N-terminus of peptide
  • carbodiimide (EDC), - attaches carrier to C-terminus of peptide
  • succinimide esters (e.g. MBS, SMCC) - binds free amino group and Cys residues
  • benzidine (BDB), - links to Tyr residues
  • periodate, - attaches to carbohydrate groups

Bioconjugate chemistry may occur through the C- and N-terminals of each polypeptide chain, the carboxylate groups of aspartic and glutamic acids, the ϵ-amine of lysine, the guanidino group of arginine, the sulfhydryl group of cysteine, the phenolate ring of tyrosine, the indol ring of tryptophan, the thioether of methionine, and the imidazole ring of histidine.

Service Specification

After standard desalting, or purification, a small percent of heterogeneous products containing single or multi-site conjugate per molecule may exist.


  • Peptide and amino acids
    • Amino acids: Asp, Glu, Lys, Arg, Cys,Tyr, Trp, Met, His
    • Synthetic peptides
  • Biopolymers
    • Protein: Enzyme, antibodies, antigens, cell adhesion molecules
    • Peptides: Synthetic polypeptides
    • Saccharides: Sugars, oligosaccharides, and polysaccharides
    • Lipids: Fatty acids, phospholipids, glycolipids, and any fat-like substances.
    • Ligands: Hormone receptors, cell surface receptors, avidin and biotin, small molecules
    • Labels: Fluorescent dyes, infrared-absorbing and UV-Vis absorption chromophores, nonradioactive labels
    • Nucleic acids and nucleotides: DNA, RNA, BNA, nucleic acid analogs and genomic DNA
    • Synthetic polymers: PEG, Nanoparticles, gold particles, dendrimers, dendron, PAMAM
    • Others: Conjugated or mixtures of any the above
    • Solid Supports: agarose, glass plates, membrane, beads


All custom synthesis of biomolecules, modification, or bioconjugation services are manufactured under strict quality control processes.Analytical HPLC and MS analyses are performed in every development cycle. Final target conjugates must first be isolated from excess or unreacted reagent. In many cases, simple dialysis may suffice to remove unreacted reagent from the reaction solution. Depending on the project scope, size-exclusion chromatography (SEC) or HPLC may also be used to either remove excess reagent or to isolate and characterize the cross-linked product. The cross-linked target molecule may then be further characterized by biochemical or biophysical techniques. Once the product has been purified, it may be subject to various characterization methods including spectrometric (MALDI-TOF, ESI, LC-MS), fluorescence, electrophoresis, and immunochemical, biochemical, and enzymatic analysis. QC (quality control) and QA (quality assurance) procedures are also followed independently to ensure the highest quality possible of every delivered conjugate. Moreover, our dedicated technical account managers will guide your project through every step of the process and keep you informed of the latest progress.

Delivery Specifications

The typical delivery consists of lyophilized sample in individual fully labeled vials. The shipment also contains COA, MS, HPLC and/or other analytical data. Additional analytical data is also available upon request.

If you can't find what you want? Please contact us online with your detail project descriptions.


Price varies based on the project specifications. Our service includes materials and labor for conjugation only! Price does not include the cost of biopolymer synthesis or purchase from a commercial vendors other than Bio-Synthesis and, if deemed necessary, biopolymer modification to introduce additional functional groups, extra linkers, spacers. Please contact us for a quote.

Basic Biopolymer Modification BIOCON10000
N-terminus Modification BIOCON11000
Acetylation (Ac) BIOCON11001
Formylation BIOCON11002
Fatty Acid BIOCON11003
Benzoyl (Bz) BIOCON11004
Benzyloxycarbonylation (CBZ) BIOCON11005
Bromoacetylation (Br-Ac) BIOCON11006
Pyroglutamyl (pGlu) (Pyr) BIOCON11007
Succinylation (Suc) BIOCON11008
Tertbutoxycarbonyl (Boc) BIOCON11009
3-Mercaptopropyl (Mpa) BIOCON11010
Myristoylation BIOCON11012
C-terminus Modifications BIOCON11013
Amidation BIOCON11014
Aldehyde BIOCON11016
Alcohol BIOCON11017
Ester (OMe, OEt) BIOCON11018
p-Nitroaniline (pNA) BIOCON11019
NHMe, NHEt and Nhisopen BIOCON11020
tBu BIOCON11021
TBzl BIOCON11022
Cysteamide (Cya) BIOCON11023
Chloromethyl Ketones BIOCON11024
Hydrazides BIOCON11025
N-Alkyl amides BIOCON11026
Thioester BIOCON11027
Thiols (-SH) BIOCON11028
Other Modifications BIOCON11029
Biotin and FITC Labeling BIOCON11030
Disulfide Bridge BIOCON11031
Phosphorylation BIOCON11032
BSA, KLH, OVA Conjugation BIOCON11033
Peptide PEGylation BIOCON11034
Quenched Fluorescent Peptide BIOCON11036
Special Amino Acid BIOCON11037
Methyl and N-Methyl BIOCON11038
Click Chemistry: Azide or Alkyne modification BIOCON11039
Amino acid BIOCON11040
Lipopeptide modifications - Preny, Farnesyl, Geranylgeranyl BIOCON11041
Amino Acid Modification BIOCON11042
Phosphorylation of Ser, Thr, Tyr BIOCON11043
Free SH on Cysteine BIOCON11044
Heavy Isotope labeling BIOCON11045
Alkyne BIOCON11046
Azide BIOCON11047
Dehydroalanine BIOCON11048
Dehydroleucine BIOCON11049
Dehydroproline BIOCON11050
Sulfated Tyrosine BIOCON11051

Ordering and Submitting Requests for Bioconjugation Services

For us to better understand your customized project, please complete our Bioconjugation Service Questionnaire. The more our chemists understand your project’s needs, the more accurate your provided feedback will be. Providing us with your project’s details enables us to recommend the best reagents to use for your project. The most useful and readily available tools for bioconjugation projects are cross-linking reagents. A large number of cross-linkers, also known as bifunctional reagents, have been developed. There are several ways to classify the cross-linkers, such as the type of reactive group, hydrophobicity or hydrophilicity and the length of the spacer between reactive groups. Other factors to consider are whether the two reactive groups are the same or different (i.e. heterobifunctional or homobifunctional reagents), spacer is cleavable and if reagents are membrane permeable or impermeable. The most accessible and abundant reactive groups in proteins are the ϵ-amino groups of lysine. Therefore, a large number of the most common cross-linkers are amino selective reagents, such as imidoesters, sulfo-N-hydroxysuccinimide esters and N-hydroxysuccinimide esters. Due to the high reactivity of the thiol group with N-ethylmaleimide, iodoacetate and a-halocarbonyl compounds, new cross-linkers have been developed containing maleimide and a-carbonyl moieties. Usually, N-alkylmaleimides are more stable than their N-aryl counterparts.

In addition to the reactive groups on the cross-linkers, a wide variety of connectors and spacer arms have also been developed. The nature and length of the spacer arm play an important role in the functionality. Longer spacer arms are generally more effective when coupling large proteins or those with sterically protected reactive side-chains. Other important considerations are the hydrophobicity, hydrophilicity and the conformational flexibility. Long aliphatic chains generally fold on themselves when in an aqueous environment, making the actual distance spanned by such linker arms less than expected. Instead, spacers containing more rigid structures (for example, aromatic groups or cycloalkanes) should be used. These structures, however, tend to be very hydrophobic which could significantly decrease the solubility of the modified molecules or even modify some of their properties. In such cases, it is recommended to choose a spacer that contains an alkyl ether (PEO) chain. Bio-Synthesis offers several cross-linkers with PEO chains, such as thiol-binding homobifunctional reagents, heterobifunctional bases and their derivatives.

Within 3-5 days upon receiving your project scope, we will provide you an appropriate quotation. An order can be placed with PO (Purchase Order) or major credit cards ( ). Your credit card will be billed under Bio-Synthesis, Inc.