Type of Immunogen Carriers
The most commonly used carriers are all highly immunogenic, large molecules that
are capable of eliciting immuno-response when couple to hapten. Several type of
immunogenic oligo-carrier conjugates offers in our laboratory.
- Protein carries: KLH, BSA, Tyroglobulin, OVA, Tetanus and Diptheria Toxoids
- Lipsome-oligonucleotide conjugates
- Synthetic or natural polymers (dextran, agarose, poly-L-lysine), or
- Synthetically designed organic molecules (dendrimers).
The primary criteria for a carrier molecule are the potential for immunogenicity,
the presence of suitable functional group for conjugation with oligo or nucleic
acid should be available for conjugation. Bio-Synthesis conjugation services include
biopolymer modification, activation and conjugation.
Please contact us for a quotation.
The coupling chemistry used to prepare an immunogen from DNA or cDNA and carrier
protein is an important consideration for the successful production and correct
specificity of the resultant antibodies. The selection on the type of crosslinking chemistries is governed by the functional groups present on the carrier and the
oligo/nucleic acid, as well as, the orientation of the hapten desired for appropriate
presentation to the immune system. The antibody recognition and cross-reactivity
toward the crosslinking reagent should consider carefully. If antibodies are generated against the crossliker bridge connecting the carrier with the oligos, then this may dilute the desired antibody response against the oligonucleotide.
Various cross-linking strategies can be used to conjugate peptide with oligonucleotide. Contact us for chemistries in addition to:
- Carbodiimide-Mediated (EDC) amide bond formation through the use of functional groups from a carrier and carboxyl modified oligonucleotide.
- NHS Ester-Maleimide Heterobifunctional Crosslinker-Mediated Hapten-Carrier Conjugation commonly used in our laboratory by activating the carrier with SMCC to create an intermediate maleimide derivatives. The maleimide groups then can be coupled to thiols modified
oligo to form thioether bonds.
- Reductive Amination Mediated Hapten-Carrier Conjugation: Aldehyde modified DNA oligomer can be crosslinked to carrier molecules by use of reductive amination.
Depending on project specification, a pool of heterogeneous products in small percentage may exist.
Functionalization of oligo is manufactured under strict quality control process.
Analytical HPLC and MS analyses are performed in every development cycle. Depending on the type of conjugation chemistry we use, after buffer exchange (if necessary) conjugates undergo gel filtration or through use of the centrifugal concentrator to remove excess crosslinking reagents and oligonucleotides. Finally concentration is determined, as well as gel electrophoresis analysis of the DNA-KLH and other carrier conjugates.
Whereas we can chemically link the intended components of a conjugated molecule;
there exists the possibility that the binding sites/active sites of the protein can
be altered/modified, partially or completely, independent of the stoichiometry used.Sometimes this activity loss is caused by physically blocking the antigen binding
sites during conjugation or by conformational changes in the complement-determining regions. Some proteins/antibodies are just too labile to undergo chemical modification reactions, regardless of the coupling methods used.
Bio-Synthesis can only guarantee the structure of our conjugates but not the suitability to specific biological applications
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.