Description

Fmoc-N-amido-dPEG®36-TFP ester, product number QBD-11008 contains an Fmoc-protected amine on one end of a long (112 atoms), single molecular weight, discrete-chain-length polyethylene glycol (dPEG®) spacer and the tetrafluorophenyl (TFP) ester of a propionic acid group on the other end. This product is ready for the direct introduction of a water-soluble, amphiphilic spacer into a peptide chain. The Fmoc protecting group on the N-terminus of the molecule cleaves easily with standard peptide chemistry.

Fmoc-N-amido-dPEG®36-TFP ester permits our customers to insert a dPEG® spacer into a peptide chain using standard Fmoc chemistry without the need to activate the acid terminus for conjugation. The product works in solid-phase and solution-phase synthetic processes; however, it may work better in solution-phase syntheses because of the dPEG® spacer’s length. In aqueous solutions, TFP esters are more hydrolytically stable than NHS esters and have an optimum pH range of 7.5 – 8.0 for conjugation. The dPEG® linker attaches at the N-terminal end of the peptide chain or on the free amine side chain of amino acids such as lysine. Additional peptide synthesis can be carried out to extend the peptide further, creating a peptide with a flexible, hydrophilic linker or spacer in the middle or joining two different peptides across the dPEG® bridge. In addition, the dPEG® chain can provide spacing in a synthetic construct where steric hindrance is a problem. Amphiphilic, non-immunogenic dPEG® increases the hydrodynamic volume and improves the water solubility of the conjugate while remaining soluble in organic solvents. The Fmoc protecting group is removed easily with a solution of piperidine in N,N-dimethylformamide (DMF).

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

Amino-dPEG®36-acid, product number QBD-10907, is a PEGylated amino acid. A primary amine group and a propionic acid group sit on opposite ends of a long (111 atoms, 132.7 Å), single molecular weight polyethylene glycol (PEG) spacer with a discrete chain length (dPEG®). The highly hydrophilic, discrete PEG spacer (Ð = 1) increases the hydrodynamic volume and imparts water solubility to conjugates that incorporate it. Moreover, Amino-dPEG®36-acid may benefit numerous applications, including peptide synthesis, peptide modification, surface modification, oligonucleotide sequencing, drug delivery, and small molecule modification.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0). Specifically see pp. 726-729 in his Chapter 18 on discrete PEG compounds for pegylation applications.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See chapter 18, Discrete PEG Reagents, pp.787-821, for a full overview of the dPEG® products.

PEG-Labeled Nucleotides and Nanopore Detection for Single Molecule DNA Sequencing by Synthesis. Shiv Kumar, Chuanjuan Tao, Minchen Chien, Brittney Hellner, Arvind Balijepalli, Joseph W. F. Robertson, Zengmin Li, James J. Russo, Joseph E. Reiner, John J. Kasianowicz & Jingyue Ju. Scientific Reports. 2012, 2 (684). September 21, 2012. DOI: 10.1038/srep00684.

Description

CBZ-N-amido-dPEG®36-acid, product number QBD-10906, is a benzyl carbamate (Cbz) N-protected amino-dPEG®-acid that provides a long (111 atoms, 132.7 Å), single molecular weight discrete PEG (dPEG®) spacer. It can be used in peptide synthesis to modify the side chain of lysine and in other forms of supramolecular construction. The Cbz protecting group is stable to acidic and basic conditions and is most easily removed using palladium black or palladium on carbon with hydrogen. This makes Cbz removal orthogonal to most other peptide synthesis deprotection reactions.

CBZ-N-amido-dPEG®36-acid works well in solution-phase synthesis. Carbodiimide activation, with or without an acylating agent, permits conjugation of the acid terminus of the dPEG® product to free amines. Other synthetic processes (e.g., surface modification, supramolecular construction) requiring the attachment or insertion of a medium-length PEG linker or spacer can employ CBZ-N-amido-dPEG®36-acid profitably also.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

MAL-dPEG®36-NHS ester, product number QBD-10904, is a crosslinking reagent that joins a sulfhydryl to a free amine through a hydrophilic bridge. The sulfhydryl groups react with a maleimide group via a Michael addition reaction. The amines form amide bonds with the crosslinker by nucleophilic substitution of the N-hydroxysuccinimidyl (NHS) ester of a carboxylic acid group. The maleimide and NHS functional groups on the crosslinking compound sit at either end of a long (118 atoms, 134.8 Å), discrete-length polyethylene glycol (dPEG®) chain.

Reactions that join free amines with free thiols are among the most popular, most useful crosslinking reactions in bioconjugate chemistry. These reactions require heterobifunctional reagents that bridge the two groups. Traditional crosslinkers are hydrophobic molecules. Vector Laboratories’ dPEG® crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths.

The conjugation of conventional hydrophobic crosslinking reagents to biomolecules almost inevitably triggers problems such as aggregation and precipitation of the conjugates. These problems do not occur with our water-soluble, non-immunogenic dPEG® crosslinkers.

Because NHS esters hydrolyze readily in water or aqueous buffer, the NHS ester end of the molecule must conjugate to a target molecule before conjugating the maleimide end of the molecule. At pH 7.0 – 7.5, NHS esters react optimally with free amines. However, NHS esters can react with free amines with pH as low as 6.5. As the pH increases, the hydrolysis rate of the NHS ester increases. Indeed, at pH 8 and 25°C, the half-life of an NHS ester in aqueous media is one hour, while at pH 8.6 and 4°C, the half-life falls to ten (10) minutes.[3] Thus, we strongly discourage storing MAL-dPEG®36-NHS ester, product number QBD-10904, in water or aqueous buffer. Instead, we recommend that customers make new solutions of the product as needed, use them immediately, and discard unused solutions after use.

The reaction of the maleimide end of MAL-dPEG®36-NHS ester with a sulfhydryl proceeds optimally at pH 6.5 – 7.5. Use the lowest reasonable pH within this range. Above pH 7.5, free amines compete with free thiols at the maleimide reaction site, which can cause confusing results. Moreover, at higher pH values, the maleimide ring may open to form unreactive maleamic acid.

The use of MAL-dPEG®36-NHS ester, product number QBD-10904, has been published in numerous scientific paper and patents. The following list highlights some of the more interesting uses of this product:
development of extracellular drug conjugates (EDCs), a type of ADC for extracellular markers;
targeted delivery of cancer drugs;
as a long, flexible tether for atomic force microscopy (AFM); and
as a surface coating for amine-functionalized nanoparticle surfaces.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0); See pp. 276-335 for general description and use of heterobifunctional crosslinkers, as well as his specific discussion with protocols of our MAL-dPEG®x-NHS esters on pp. 718-722.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

“Fmoc-N-amido-dPEG®36-acid, product number QBD-10903, is one of a broad line of products designed for use in peptide synthesis. The long (112 atoms), flexible, discrete PEG (dPEG®) spacer is functionalized with a propionic acid group on one end and Fmoc-protected amine on the other. The compound can be added to the N-terminus of a growing peptide chain or to a primary-amine-functionalized side chain of an amino acid such as lysine. The non-immunogenic dPEG®36 spacer increases the hydrodynamic volume and imparts water solubility to the conjugate molecule.

QBD-10903 permits our customers to insert a dPEG® spacer into a peptide chain using familiar Fmoc chemistry using solid phase or solution phase chemistry. However, due to the spacer’s length, it may work better in solution-phase syntheses. The dPEG® compound can be inserted at either end of the peptide chain or in the middle of two amino acid sequences to provide a flexible linker between distinct functional peptides. Additionally, the dPEG® spacer can be used to provide spacing in a synthetic construct where steric hindrance is a problem. The amphiphilic nature of dPEG® products means that the construct gains hydrodynamic volume and water solubility while remaining soluble in organic solvent. The Fmoc protecting group is removed easily with a solution of piperidine in N,N-dimethylformamide (DMF).”

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Lipo-Oligomer Nanoformulations for Targeted Intracellular Protein Delivery. Peng Zhang, Benjamin Steinborn, Ulrich Lachelt, Stefan Zahler, and Ernst Wagner. Biomacromolecules. 2017, June 26, 2017. DOI: 10.1021/acs.biomac.7b00666.

Flexible antibodies with nonprotein hinges. Daniel J. Capon, Naoki Kaneko, Takayuki Yoshimori, Takashi Shimada, Florian M. Wurm, Peter K. Hwang, Xiaohe Tong, Staci A. Adams, Graham Simmons, Taka-Aki Sato and Koichi Tanaka. The Japan Academy, Series B. 2011, 87 (9) pp 603-616. November 11, 2011. DOI: 10.2183/pjab.87.603.

A Systematic Analysis of Peptide Linker Length and Liposomal Polyethylene Glycol Coating on Cellular Uptake of Peptide-Targeted Liposomes. Jared F. Stefanick, Jonathan D. Ashley, Tanyel Kiziltepe, and Basar Bilgicer. ACS Nano. 2013, 7 (4) pp 2935–2947. February 19, 2013. DOI: 10.1021/nn305663e.

Enhanced Cellular Uptake of Peptide-Targeted Nanoparticles through Increased Peptide Hydrophilicity and Optimized Ethylene Glycol Peptide-Linker Length. Jared F. Stefanick, Jonathan D. Ashley, and Basar Bilgicer. ACS Nano. 2013, 7 (9) pp 8115–8127. August 29, 2013. DOI: 10.1021/nn4033954.

PEG-Peptide Conjugates. Ian W Hamley. Biomacromolecules. 2014, 15 (5) pp 1543-1559. April 1, 2014. DOI: 10.1021/bm500246w.

Evaluation of Nonpeptidic Ligand Conjugates for SPECT Imaging of Hypoxic and Carbonic Anhydrase IX-Expressing Cancers. Peng-Cheng Lv, Karson S. Putt, and Philip S. Low. Bioconjugate Chemistry. 2016, 27, pp 1762-1769. June 30, 2016. DOI: 10.1021/acs.bioconjchem.6b00271.

Bioresponsive nanocarries for targeted intracellular delivery of proteins and peptides. Ruth Elisabeth and Johanna Roder. Dissertation zur Erlangung des Doktorgrades der Fakultat fur Chemie und Pharmazie der Ludwig-Maximilians-Universitat Munchen. 2016, pp 1-128.

Efficient capture of circulating tumor cells with low molecular weight folate receptor-specific ligands. Yingwen Hu, Danyang Chen, John V Napoleon, Madduri Srinivasarao, Sunil Singhal, Cagri A Savran, Philip S Low. Scientific Reports. 2022. May 20, 2022. https://doi.org/10.1038/s41598-022-12118-3

Description

t-boc-N-amido-dPEG®36-acid, product number QBD-10902, is composed of a boc-protected primary amine and a propionic acid group on opposite ends of an extended (111 atoms, 132.7 Å), single molecular weight, discrete PEG (dPEG®) linker. Designed for use in Boc-based peptide chemical synthesis, t-boc-N-amido-dPEG®36-acid can be used to insert a discrete PEG linker/spacer at the N-terminus of a peptide chain or to add a dPEG® onto the side chain of an amino acid such as lysine or ornithine. Insertion of t-boc-N-amido-dPEG®36-acid at the N-terminus of a peptide allows the creation of a flexible, hydrophilic bridge to the C-terminus of another peptide. The Boc protecting group cleaves easily under acidic conditions with, for example, TFA. This compound can also be used to modify amine-functionalized surfaces to passivate them with a hydrophilic spacer. Removal of the boc group with acid allows for functionalization of the surface with peptides, proteins, or small molecules.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

Amino-dPEG®36–t-butyl ester, product number QBD-10901, is a long (111 atoms, 132.7 Å), heterobifunctional, monodisperse polyethylene glycol (PEG) linker containing a single molecular weight, discrete length PEG (dPEG®) chain. One end of the dPEG® chain terminates with a carbonyl-reactive primary amine. The opposite end terminates with an amine-reactive, tert-butyl-ester-protected propionic acid. The t-butyl ester protecting group cleaves easily with trifluoroacetic acid (TFA), exposing a propionic acid moiety that forms amide bonds with primary amines upon activation. This compound is useful for supramolecular construction and building novel crosslinkers. Conjugates modified with QBD-10901 have improved water solubility and greater hydrodynamic volume.

The amine end of the molecule reacts with activated carboxylic acid esters (for example, N-hydroxysuccinimidyl or tetrafluorophenyl esters) to form an amide bond. Also, carboxylic acids can couple to the amine end of Amino-dPEG®36-t-butyl ester using a carbodiimide such as EDC, with or without an acylating agent such as N-hydroxysuccinimide (NHS). After working up the reaction to remove unreacted components and isolate the intermediate, trifluoroacetic acid is used to remove the tert-butyl ester and expose the propionic acid end group. The exposed carboxylic acid can then react further. For example, activation as the NHS or TFP ester is possible. Also, the acid can be coupled directly to an amine as described above.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

Lipoamido-dPEG®36-TFP ester, product number QBD-10644, is a single molecular weight, discrete PEG (dPEG®) modification reagent. The product consists of alpha-lipoic acid and a 2,3,5,6-tetrafluorophenyl (TFP) ester on opposite ends of a long (120 atoms) dPEG® spacer. The lipoic acid group forms two (2) coordinate covalent bonds (dative bonds) with metal, especially gold and silver. The TFP ester reacts with free amines to form amide bonds. Applications for this product include peptide or protein immobilization on metal surfaces, the formation of self-assembled monolayers (SAMs) on metal surfaces, and sensor development.

Lipoic acid, also known as α-lipoic acid and thioctic acid, is a naturally occurring antioxidant that functions as a cofactor in several enzyme systems. It consists of a dithiolane ring (a five-membered ring containing a disulfide) attached to a pentanoic acid group. As a bidentate thiol ligand, lipoic acid forms two stable dative bonds per lipoic acid group with gold, silver, and other metals. These dative bonds form with oxidized lipoic acid or reduced dihydrolipoic acid (DHLA). Because it forms two dative bonds on metal surfaces, lipoic acid is more stable than PEGylation reagents containing a single thiol. This increased stability prevents lipoic-acid-functionalized dPEG® products from being oxidized off the metal surface.

When using this product, it is typical to begin with the conjugation of the carboxyl end of the dPEG® to an amino group to form an amide bond. As documented in the scientific literature, TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimidyl (NHS) esters. TFP esters optimally react with amines at pH 7.5 – 8.0.

After reacting the TFP ester end of the molecule, the lipoic acid end of the dPEG® linker can be reacted with metals such as gold or silver. The lipoic acid group forms dative bonds with metals with or without reduction to DHLA. If reduction to DHLA is preferred, Tris(2-carboxyethyl)phosphine (TCEP) will reduce lipoic acid to DHLA rapidly.

Lipoamido-dPEG®36-TFP ester dissolves in water or aqueous buffer and organic solvents. Stock solutions in water or aqueous buffer do not have long-term stability and should be used immediately. For stock solutions with long-term stability, we recommend dry (over 3 Å molecular sieves) water-miscible solvents such as N,N-dimethylacetamide (DMAC) or acetonitrile. Unused stock solutions in dry organic solvents should be stored at -20°C or colder.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Description

DBCO-dPEG®36-TFP ester, product number QBD-10598, is a heterobifunctional, bioorthogonal crosslinker designed to join azides and amines across a long (122 atoms, 137.5 Å), flexible, hydrophilic, single molecular weight, discrete PEG (dPEG®) spacer. The tetrafluorophenyl (TFP) ester reacts specifically with free amines to form amide bonds; the optimum reaction pH is 7.5 – 8.0. The dibenzylcyclooctyne (DBCO) moiety selectively forms triazole linkages with azides via a click chemistry reaction known as strain-promoted azide-alkyne cycloaddition (SPAAC), also known as copper-free click chemistry. The amphiphilic dPEG® linker increases conjugates’ hydrodynamic volumes and water solubility, and it can be used to create space in sterically crowded supramolecular constructs.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0). Specifically see pp. 726-729 in his Chapter 18 on discrete PEG compounds for pegylation applications.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See chapter 18, Discrete PEG Reagents, pp.787-821, for a full overview of the dPEG® products.