Description

Fmoc-N-amido-dPEG®8-TFP ester, product number QBD-11005 contains an Fmoc-protected amine on one end of a short (28 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®8-TFP ester permits our customers to insert a short dPEG® spacer into a peptide chain using standard Fmoc chemistry without the need to activate the acid terminus for conjugation. The product works equally well in solid-phase and solution-phase synthetic processes. 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

Fmoc-N-amido-dPEG®8-NHS ester, product number QBD-10995 contains an Fmoc-protected amine on one end of a short (28 atoms), single molecular weight, discrete-chain-length polyethylene glycol (dPEG®) spacer and the N-hydroxysuccinimidyl (NHS) 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 without the need to activate the carboxylic acid moiety. The Fmoc protecting group on the N-terminus of the molecule cleaves easily with standard peptide chemistry.

Fmoc-N-amido-dPEG®8-NHS ester permits our customers to insert a short dPEG® spacer into a peptide chain using solid-phase or solution-phase chemistry. 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. Also, 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 peptide 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.

Design of a modular tetrameric scaffold for the synthesis of membrane-localized D-peptide inhibitors of HIV-1 entry. J. Nicholas Francis, Joseph S Redman, Debra M Eckert, and Michael S. Kay. Bioconjugate Chemistry, 2012, 23 (6), pp 1252-1258, May 1, 2012. DOI: 10.1021/bc300076f.

Novel Synthetic Route to Peptide-Capped Gold Nanoparticles, Takeshi Serizawa, Yu Hirai, and Mamoru Aizawa. Langmuir. 2009, 25 (20), pp 12229–12234. September 21, 2009. DOI: 10.1021/la9021799.

Multivalent Benzamidine Molecules for Plasmin Inhibition: Effect of Valency and Linker Length. Tanmaye Nallan Chakravarthula, Dr. Ziqian Zeng, Prof. Nathan J. Alves. ChemMedChem, Volume 17, Issue 22, (2022), 09/16/2022, https://doi.org/10.1002/cmdc.202200364.

Description

Amino-dPEG®8-t-boc hydrazide, product number QBD-10957, is a useful molecular modification and bioconjugation reagent consisting of a free, primary amine on one end of a medium-length (30 atoms, 35.9 Å) single molecular weight, discrete-chain-length polyethylene glycol (dPEG®) linker and a Boc-protected hydrazide group on the other end. The free amine reacts with carboxylic acids and their active esters to form a stable amide bond. Following the removal of the Boc protecting group, the hydrazide can be reacted with an aldehyde (for example, formed from periodate oxidation of carbohydrates) at pH 5 – 7 to form a hydrazone bond. Hydrazone bonds are acid labile but otherwise stable, thus allowing the conjugate or supramolecular construct to degrade under acidic conditions such as in lysosomes or the acidic extracellular microenvironments at inflammation or tumor metastasis sites. The single molecular weight, discrete PEG (dPEG®) crossbridge is water-soluble and non-immunogenic, and it adds flexibility and increases the hydrodynamic volume of conjugates and supramolecular constructs that incorporate it.

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®8-acid, product number QBD-10806, is a single molecular weight, discrete PEG (dPEG®) surface modification reagent for metal surfaces, especially gold and silver. The hydrophilic dPEG®8 spacer is 36 atoms (41.2 Å) long. The lipoamide moiety rapidly forms stable dative bonds with gold or silver. Using a carbodiimide such as EDC and an acylating agent such N-hydroxysuccinimide (NHS), the propionic acid group will react with free amines to form amide bonds. The water-soluble, non-immunogenic dPEG® spacer adds hydrodynamic volume to conjugates made with this product. For circulating nanoparticles, the increased hydrodynamic volume reduces or eliminates opsonization and facilitates a longer circulation time in vivo.

Lipoic acid, also known as thioctic acid and alpha-lipoic acid (ALA), is an organosulfur compound used by cells as an essential cofactor. The sulfur atoms at positions C6 and C8 form a disulfide bond in a five (5)-membered ring. Like other thiol products, lipoic acid readily forms dative bonds with gold, silver, and other metals. Because two dative bonds form for each molecule of lipoic acid, the thiol-metal dative bond is more stable than dative bonds formed with compounds containing one free thiol atom. Lipoic acid exists typically in an oxidized (closed ring) state. It is readily reduced to an open ring state called dihydrolipoic acid (DHLA) using tris(2-carboxyethyl)phosphine (TCEP) or other reducing agents.

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), pp 188-190, 458-497, 924-935.

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.

Site-Specific Conjugation of Antibody on Gold Nanoparticle Surface for One-Step Diagnosis of Prostate Specific Antigen with Dynamic Light Scattering. Nur Mustafaoglu, Tanyel Kiziltepe, and Basar Bilgicer. Nanoscale. 2017, pp 1-32. May 18, 2017. DOI: 10.1039/C7NR03096G.

Single-wavelength-excited flurogenic nanoprobe for accurate realtime ratiometric analysis of broad pH fluctuations in mitophagy. Xin Zhang, Juan Chen, Jiwen Hu, Anna du Rietz, Xiongyu Wu, Ruilong Zhang, Zhongping Zhang, Kajsa Uvdal & Zhangjun Hu. SpringerLink. 2022. May 11, 2022. https://doi.org/10.1007/s12274-022-4325-3.

Description

t-boc-N-amido-dPEG®8-acid, product number QBD-10760, is composed of a boc-protected primary amine and a propionic acid group on opposite ends of a short (28 atoms), single molecular weight, discrete PEG (dPEG®) linker. Designed for use in Boc-based peptide chemical synthesis, t-boc-N-amido-dPEG®8-acid can be used to insert a discrete PEG linker/spacer at the N-terminus of a peptide chain or to add a short dPEG® onto the side chain of an amino acid such as lysine or ornithine. Insertion of t-boc-N-amido-dPEG®8-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.

Covalently deposited dyes: a new chromogen paradigm that facilitates analysis of multiple biomarkers in situ. William A Day, Mark R Lefever, Robert L Ochs, Anne Pedata, Lauren J Behman, Julia Ashworth-Sharpe, Donald D Johnson, Eric J May, James G Grille, Esteban A Roberts, Jerry W Kosmeder, and Larry E Morrison. Laboratory Investigation. 2016, 00 pp 1-10. November 21, 2016. DOI: 10.1038/labinvest.2016.115.

Description

Lipoamido-dPEG®8-TFP ester, product number QBD-10642, is a single molecular weight, discrete PEG (dPEG®) modifier of gold and silver surfaces, for example, on nanoparticles. The lipoic acid moiety on one end of the 36-atoms-long dPEG® spacer forms dative bonds with metals like gold and silver. The TFP ester reacts with free amines to form free amines, optimally in the pH range 7.5 – 8.0. The distance from the disulfide bond in the lipoic acid ring to the carbonyl carbon adjacent to the 2,3,5,6-tetrafluorophenol (TFP) ester, the distance is 36 atoms (42.7 Å). Applications for this product include creating self-assembled monolayers (SAMs) on metal surfaces and crosslinking and immobilizing peptides and proteins to the surfaces of metal nanoparticles.

Lipoic acid, also known as alpha-lipoic acid, α-lipoic acid, and thioctic acid, consists of a five-membered ring containing a disulfide attached to a pentanoic acid group. As a naturally occurring antioxidant, lipoic acid functions as a cofactor in several enzyme systems. It is a bidentate thiol ligand that 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. 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 rapidly reduce lipoic acid to DHLA.

TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimidyl (NHS) esters. The superiority of PEG-TFP esters over NHS esters is documented in the scientific literature. When using this product, it is typical to conjugate the carboxyl end of the dPEG® to an amine to form an amide bond before forming a dative bond between a metal surface and the lipoic acid moiety of Lipoamido-dPEG®8-TFP ester. The TFP ester reacts optimally at pH 7.5 – 8.0, but it will also react with amines at pH values above and below this range.

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.

Surface-Assisted Affinity Purification Mass Spectrometry (SAAP-MS)for Determination of Enzyme Activities. Yang. Hyojik. UC Riverside Electronic Theses and Dissertations. 2016, pp 1-221. June 2016. http://escholarship.org/us/item/2qv796zz.

Description

MAL-dPEG®8-TFP ester, product number QBD-10552, is a crosslinking reagent that joins free amines to free thiols (sulfhydryl groups) across a medium-length (38 atoms), single molecular weight, discrete PEG (dPEG®) linker. The sulfhydryl groups react with a maleimido group via a Michael addition reaction. The amines form amide bonds with the crosslinker by nucleophilic substitution of the 2,3,5,6-tetrafluorophenyl (TFP) ester of the terminal propionic acid group.

The conjugation of free amines to free thiols is one of the most popular, most useful crosslinking reactions in bioconjugate chemistry is the conjugation of free amines to free thiols. These reactions require heterobifunctional reagents that bridge the two groups. Typical crosslinkers are hydrophobic. Vector Laboratories’ dPEG® crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths. These hydrophilic, non-immunogenic, dPEG® crosslinkers prevent the problems with aggregation that arise when using traditional, hydrophobic crosslinkers.

Published studies have shown that TFP esters are more hydrolytically stable in aqueous buffers than N-hydroxysuccinimidyl (NHS) esters and are more reactive toward free amines. TFP esters react under the same conditions as NHS esters. However, the optimal pH range for TFP esters (7.5 – 8.0) is slightly higher than for NHS esters (7.0 – 7.5). Amide bond formation between the TFP-activated propionic acid group of MAL-dPEG®8-TFP ester and a free amine will be slightly slower at a suboptimal pH compared to the reaction rate within the optimum pH range.

The maleimide end of MAL-dPEG®8-TFP ester, product number QBD-10552, reacts optimally with a sulfhydryl at pH 6.5 – 7.5. Conduct the conjugation at the lowest reasonable pH within this range. Above pH 7.5, free amines compete with free thiols at the maleimide reaction site, which may confound the data. Moreover, at higher pH values, the maleimide ring may open to form unreactive maleamic acid.

MAL-dPEG®8-TFP ester, product number QBD-10552, can be used the same way and in the same applications as the equivalent NHS esters. Possible uses for this product include the following:
Coating nanoparticle surfaces;
Tethering antibodies to atomic force microscopy (AFM) probes;
Constructing antibody-drug conjugates (ADCs);
Adding flexibility and water solubility to a peptide;
Increasing the water solubility and hydrodynamic volume of hydrophobic biomolecules;
Building supramolecular constructs; and,
Conjugating the TFP ester end of the molecule a liposomal surface and then using the free maleimide end of the molecule to attach a small molecule drug, peptide, or antibody for targeted delivery of a diagnostic or therapeutic package.

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.

An Investigation of Phosphorous-Based Bioconjugation Techniques for Protein Modification. Maja Lopandic. UWSPACE. 2022. April 7, 2022. http://hdl.handle.net/10012/18138.

Description

Azido-dPEG®8-OH (Azido-dPEG®8-alcohol), product number QBD-10542, is a click chemistry reagent used to modify surfaces and biomolecules or to crosslink with other surfaces or biomolecules in supramolecular construction. This product consists of an azide and a terminal hydroxy group separated by a medium-length (24 atoms), single molecular weight, discrete-length polyethylene glycol (dPEG®) chain. The terminal azide reacts in copper(I)-catalyzed, ruthenium-catalyzed, and strain-promoted azide-alkyne cycloaddition reactions (CuAAC, RuAAC, and SPAAC, respectively). If left unmodified, the alcohol group increases the water solubility and hydrodynamic volume of molecules and surfaces to which it is conjugated. Modifying the alcohol with a reactive group such as chloride, tosylate, or mesylate allows Azido-dPEG®8-OH to function as a crosslinker through subsequent chemical manipulations.

As a click chemistry reagent, azido-dPEG®8-OH can participate in CuAAC, RuAAC, and SPAAC reactions. Because Vector Laboratories’ dPEG® products are amphiphilic, these reactions can occur almost equally well in water or organic solvents. Thus, azido-dPEG®8-OH can be used in conjugations with biomolecules where organic solvents may damage the conjugate target.

The primary alcohol group on the opposite end of the linker can be used as a neutrally charged functional group. In this function, the alcohol enhances the water solubility of the conjugate molecule. Alternatively, the alcohol group can be functionalized with reactive groups and used to modify the conjugate further.

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

Azido-dPEG®8-acid, product number QBD-10512, is a click chemistry reagent consisting of an azide group on one end of a medium-length (28 atoms), single molecular weight PEG linker with a discrete chain length (dPEG®) and a propionic acid group on the other end. The azide moiety can be used for copper(I)-catalyzed click chemistry or copper free click chemistry. The propanoic acid moiety can be coupled to a primary or secondary amine by an acylation reaction. The amphiphilic dPEG® linker adds water solubility to conjugated molecules.

Activation of the propanoic acid moiety with an acylating agent enables conjugation of azido-dPEG®8-acid to a primary or secondary amine. Popular acylating agents include such as N-hydroxysuccinimide (NHS); 2,3,5,6-tetrafluorophenol (TFP); or 2,3,4,5,6-pentafluorophenol (PFP). Alternatively, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) or another suitable carbodiimide can be used to couple the acid moiety directly to an amine without prior activation.

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.

“Click” Immobilization of a VEGF-Mimetic Peptide on Decellularized Endothelial Extracellular Matrix to Enhance Angiogenesis. Lin Wang, Meirong Zhao, Siheng Li, Uriel J. Erasquin, Hao Wang, Li Ren, Changyi Chen, Yingjun Wang, and Chengzhi Cai. ACS Applied Materials and Interfaces. 2014, 6 (11) pp 8401-8406. April 21, 2014. 10.1021/am501309d.

Description

Azido-dPEG®8-NHS ester, product number QBD-10503, is a water-soluble click chemistry crosslinker containing an azide group linked to an N-hydroxysuccinimidyl (NHS) ester through a single molecular weight, discrete polyethylene glycol (dPEG®) spacer. Azido-dPEG®8-NHS ester works with copper(I)-catalyzed, ruthenium-catalyzed and with copper-free (e.g., strain-promoted) click chemistry. The dPEG® spacer imparts water solubility and adds hydrodynamic volume to the conjugated product. The single molecular weight product design, with its discrete chain length, simplifies the analysis of this product.

Our single molecular weight, discrete chain length PEG (dPEG®) products are a superior alternative to traditional polyethylene glycol products. Conventional PEGylation reagents consist of a complex mixture of different chain lengths due to the polymerization processes that form them. In contrast, each dPEG® product contains a discrete chain length of PEG with only one molecular weight. Conjugates made with dPEG® products have less complicated analyses compared to conjugates prepared with traditional PEGylation reagents.

NHS esters are the most popular, most widely used way to conjugate carboxylic acids to primary or secondary amines resulting in stable amide bonds. NHS esters react quickly and efficiently in aqueous media at physiological pH values (7.0 – 7.5). However, they are prone to hydrolysis at a rate that is pH-dependent. Published research shows that 2,3,5,6-tetrafluorophenyl (TFP) esters are more hydrolytically stable and have better reactivity with amines than NHS esters.

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.

A Modular Platform for the Rapid Site-Specific Radiolabeling of Proteins with F Exemplified by Quantitative Positron Emission Tomography of Human Epidermal Growth Factor Receptor 2. Herman S. Gill, Jeff N. Tinianow, Annie Pgasawara, Judith E. Flores, Alexander N. Vanderbilt, Helga Raab, Justin M. Scheer, Richard Vandlen, Simon-P. Williams, and Jan Marik, J. Med. Chem., 2009, 52 (19), pp 5816–5825 September 9, 2009. DOI: 10.1021/jm900420c.

An Effective Targeted Nanoglobular Manganese(II) Chelate Conjugate for Magnetic Resonance Molecular Imaging of Tumor Extracellular Matrix. Mingqian Tan, Xueming Wu, Eun-Kee Jeong, Qianjin Chen, Dennis L. Parker, and Zheng-Rong Lu,Mol. Pharmaceutics, 2010, 7 (4), pp 936–943 May 19, 2010. DOI: 10.1021/mp100054m.

Constant-speed vibrational signaling along polyethylene glycol chain up to 60-Å distance. Zhiwei Lin and Igor V. Rubtsov. PNAS, 2012, 5 (109), pp 1413-1418, January 31, 2012. DOI:10.1073/pnas.1116289109.

Ballistic energy transport along PEG chains: distance dependence of the transport efficiency. Zhiwei Lin , Nan Zhang , Janarthanan Jayawickramarajah and Igor V. Rubtsov. Physical Chemistry Chemical Physics. 2012, 30 (14), pp 10445-10454. April 12, 2012. DOI: 10.1039/C2CP40187H.

Enzymatic Ligation of Large Biomolecules to DNA. Rasmus Schøler Sørensen, Anders Hauge Okholm, David Schaffert, Anne Louise Bank Kodal, Kurt V. Gothelf, and Jørgen Kjems. ACS Nano. 2013, 7 (9) pp 8098–8104. August 8, 2013. DOI: 10.1021/nn403386f.

Click Chemistry Immobilization of Antibodies on Polymer Coated Gold Nanoparticles. Chiara Finetti, Laura Sola, Margherita Pezzullo, Davide Prosperi, Miriam Colombo, Benedetta Riva, Svetlana Avvakumova, Carlo Morasso, Silvia Picciolini, and Marcella Chiari. Langmuir. 2016, 32, pp 7435-7441. July 1, 2016. DOI: 10.1021/acs.langmuir.6b01142.

Modular Assembly of Cell-targeting Devices Based on an Uncommon G-quadruplex Aptamer. Felipe Opazo, Laura Eiden, Line Hansen, Falk Rohrbach, Jesper Wengel, Jørgen Kjems, and Günter Mayer. Molecular Therapy Nucleic Acids. 2015, 4 pp e251. 9/1/2015. DOI: 10.1038/mtna.2015.25.