Description

Tetra(-amido-dPEG®11-MAL)pentaerythritol, product number QBD-11435, is a maleimide-functionalized PEG crosslinking reagent designed to join up to four molecules via a maleimide-thiol reaction. Each of the four arms of this product comes from a single molecular weight, discrete polyethylene glycol (dPEG®) spacer that is 43 atoms (47.4 Å) long, joined through a pentaerythritol core. Product applications include (1) crosslinking of proteins, peptides, or small molecules containing free sulfhydryl groups and (2) dendrimer construction with thiol-functionalized branched compounds.

The thiol-maleimide reaction, also known as the thiol-Michael addition, is a click chemistry reaction. This powerful, highly popular reaction is extensively used in bioconjugation applications. At pH 6.5 – 7.5, the thiol-maleimide reaction is chemoselective. However, above pH 7.5, the maleimide group reacts competitively with amines, so the pH should be kept below this limit.

Unlike traditional polyethylene glycol (PEG), which are non-uniform, dispersed polymers, Vector Laboratories’ dPEG® products are single molecular weight PEGs with discrete chain lengths, hence the dPEG® name.

Tetra(-amido-dPEG®11-MAL)pentaerythritol showcases one of the benefits of dPEG® linkers in product development. Each of the four dPEG® arms is identical, and the uniformity simplifies analysis. In contrast, if this product were made using traditional, non-uniform PEG compounds, analyzing it would be much more complicated and challenging.

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.

Description

Bromoacetamido-dPEG®12-Tris(-dPEG®11-amido-bromoacetamide)3, product number QBD-11434, is a branched, single molecular weight, thiol-reactive, discrete polyethylene glycol (dPEG®) product. It is designed to join up to four molecules via a thiol-bromoacetyl reaction. Each of the four arms attaches to a central tris core and terminates with a thiol-reactive bromoacetyl group. The dPEG® spacer length from between the bromoacetyl groups through the tris core is 87 atoms (100.0 Å).

Like the thiol-maleimide reaction, the thiol-bromoacetyl reaction forms stable thioether bonds with free thiols. However, maleimides react optimally at pH 6.5 – 7.5, while bromoacetyl groups react with thiols chemoselectively at pH ≥8.0. Moreover, thioether bonds formed from a thiol-maleimide reaction can sometimes undergo a reverse Michael addition, undoing the thioether bond. This does not happen with thioether bonds formed by a thiol-bromoacetyl reaction. The thiol-bromoacetyl reaction is chemoselective for thiols but slightly less selective than the thiol-maleimide reaction.

Unlike traditional polyethylene glycol (PEG), which are non-uniform, dispersed polymers, Vector Laboratories’ dPEG® products are single molecular weight PEGs with discrete chain lengths, hence the dPEG® name. The four arms of MAL-dPEG®12-Tris(-dPEG®11-amido-MAL)3 are built around a core of tris(hydroxymethyl)aminomethane (“”tris””). Although one arm is structured a little differently than the other three arms (one dPEG®12 arm vs. three dPEG®11 arms), the product is essentially symmetrical through the tris core. This precise construction of Bromoacetamido-dPEG®12-Tris(-dPEG®11-amido-bromoacetamide)3 is possible because of Vector Laboratories’ dPEG® technology. This product can link multiple peptides or proteins together for drug delivery. It could also be used as a core unit for constructing dendrimers with precisely defined spacer lengths.

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.

Description

Tetra(-amido-dPEG®23-MAL)pentaerythritol, product number QBD-11414, is a maleimide-functionalized PEG crosslinking reagent designed to join up to four molecules via a maleimide-thiol reaction. Each of the four arms of this product comes from a single molecular weight, discrete polyethylene glycol (dPEG®) spacer that is 79 atoms (89.8 Å) long, joined through a pentaerythritol core. Product applications include (1) crosslinking of proteins, peptides, or small molecules containing free sulfhydryl groups and (2) dendrimer construction with thiol-functionalized branched compounds.

The thiol-maleimide reaction, also known as the thiol-Michael addition, is a click chemistry reaction. This powerful, highly popular reaction is extensively used in bioconjugation applications. At pH 6.5 – 7.5, the thiol-maleimide reaction is chemoselective. However, above pH 7.5, the maleimide group reacts competitively with amines, so the pH should be kept below this limit.

Unlike traditional polyethylene glycol (PEG), which are non-uniform, dispersed polymers, Vector Laboratories’ dPEG® products are single molecular weight PEGs with discrete chain lengths, hence the dPEG® name.

Tetra(-amido-dPEG®23-MAL)pentaerythritol showcases one of the benefits of dPEG® linkers in product development. Each of the four dPEG® arms is identical, and the uniformity simplifies analysis. In contrast, if this product were made using traditional, non-uniform PEG compounds, analyzing it would be much more complicated and challenging.

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.

Description

MAL-dPEG®12-Tris(-dPEG®11-amido-MAL)3, product number QBD-11433, is a branched, single molecular weight, thiol-reactive, discrete polyethylene glycol (dPEG®) product. It is designed to join up to four molecules via a maleimide-thiol reaction. Built around a tris core and terminated on each arm with a thiol-reactive maleimide group, this homotetrafunctional crosslinker is 96 atoms long (124.4 Å) from one maleimide to another.

The thiol-maleimide reaction, also known as the thiol-Michael addition, is a click chemistry reaction. This powerful, highly popular reaction is extensively used in bioconjugation applications. At pH 6.5 – 7.5, the thiol-maleimide reaction is chemoselective. However, above pH 7.5, the maleimide group reacts competitively with amines, so the pH should be kept below this limit.

Unlike traditional polyethylene glycol (PEG), which are non-uniform, dispersed polymers, Vector Laboratories’ dPEG® products are single molecular weight PEGs with discrete chain lengths, hence the dPEG® name. The four arms of MAL-dPEG®12-Tris(-dPEG®11-amido-MAL)3 are built around a core of tris(hydroxymethyl)aminomethane (“”tris””). Although one arm is differently structured than the other three arms (one dPEG®12 arm vs. three dPEG®11 arms), each arm has the same number of atoms and the same length when measured from the reactive site on the maleimide to the tris core from which each arm branches. This precise construction occurs because the dPEG® spacers have discrete chain lengths. This product can link multiple peptides or proteins together for drug delivery. It could also be used as a core unit for constructing dendrimers with precisely defined spacer lengths.

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.

Description

Bis-Bromoacetamido-dPEG®11, product number QBD-11338, is a thiol-reactive, homobifunctional crosslinker, with the two reactive ends separated by a medium-length (44 atoms, 47.5 Å), single molecular weight, discrete polyethylene glycol (dPEG®) spacer. Both ends of the dPEG® spacer terminate with bromoacetyl groups that connect to the dPEG® crossbridge through amide bonds.

Bromoacetyl-functionalized reagents are useful alternatives to maleimide-functionalized reagents. The bromoacetyl group reacts with sulfhydryl groups at pH 8 or higher. Maleimide groups are chemoselective for thiols at pH 6.5 – 7.5 and lose selectivity at higher pH values. Bromoacetyl-thiol reaction rates are somewhat slower than maleimide-thiol reaction rates.

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.

Description

MAL-dPEG®24-amido-dPEG®24-TFP ester, product number QBD-11303, is a monodisperse, crosslinking PEGylation reagent that joins sulfhydryl groups to amines through a long (158 atoms, 183.5 Å), single molecular weight, discrete PEG (dPEG®) chain. One end of the crosslinker is functionalized with a maleimidopropyl (maleimide) group for reaction with free thiols, and the other end has the 2,3,5,6-tetrafluorophenyl (TFP) ester of propionic acid for reaction with free amines. The dPEG® linker consists of two dPEG®24 chains joined by an amide bond, making it functionally a dPEG®48 crosslinker with a molecular weight that is slightly more than 2000 Daltons. At pH 6.5 – 7.5, the maleimide group reacts specifically with sulfhydryl (thiol) groups to form a thioether bond. The TFP ester reacts with free amines to form amide bonds at an optimum reaction pH range of 7.5 – 8.0.

Crosslinking free thiols to free amines is one of the most popular and most useful reactions in bioconjugate chemistry. These reactions require heterobifunctional reagents that bridge the two groups. Typical, traditional crosslinkers are short and hydrophobic and frequently trigger aggregation and precipitation of conjugates made from them. In addition, traditional PEG crosslinkers use non-uniform (dispersed) polymer PEGs that consist of an intractable mixture of PEG chain lengths and molecular weights. The complexity arising from non-uniform PEG crosslinkers makes analyzing conjugates a challenging exercise.

In contrast, Vector Laboratories’ dPEG® crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths. Our dPEG® products are uniform in chain length and molecular weight (Ð = 1). This uniformity of our dPEG® products eliminates one of the most vexing analytical difficulties faced by users of traditional polymer PEG products.

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

Bromoacetamido-dPEG®24-TFP ester, product number QBD-11203, is a long (78 atoms, 91.2 Å), single molecular weight, discrete PEG (dPEG®) crosslinker functionalized with a thiol-reactive bromoacetate group on one end and an amine-reactive 2,3,5,6-tetrafluorophenyl (TFP) ester on the other.

The long, flexible, non-immunogenic dPEG® crosslinker increases the hydrodynamic volumes of conjugates in aqueous media, thereby increasing water solubility. The increased hydrodynamic volume can reduce or eliminate conjugate molecules’ renal clearance and shield conjugates from opsonization.

The bromoacetate moiety is an alternative to the maleimide group, reacting chemoselectively with free thiols at pH ≥8.0. It is useful for situations where the conjugate molecule needs to be kept at a high pH, above the range where maleimides can be used effectively, or in constructs where maleimide groups are unstable.

TFP esters are an alternate reactive group to the N-hydroxysuccinimidyl (NHS) ester and reacts with amines at an optimal pH range of 7.5 – 8.0, higher than the optimal range for NHS esters (pH 7.0 – 7.5). TFP esters are more hydrolytically stable than NHS esters, and they are more reactive toward amines in their optimal pH range than NHS esters are within the pH range 7.0 – 7.5.

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

Bromoacetamido-dPEG®12-TFP ester, product number QBD-11202, is a medium-length (42 atoms, 48.7 Å), single molecular weight, discrete PEG (dPEG®) crosslinker functionalized with a thiol-reactive bromoacetate group on one end and an amine-reactive 2,3,5,6-tetrafluorophenyl (TFP) ester on the other.

The medium-length, flexible, non-immunogenic dPEG® crosslinker increases the hydrodynamic volumes of conjugates in aqueous media, thereby increasing water solubility. The increased hydrodynamic volume can reduce or eliminate conjugate molecules’ renal clearance and shield conjugates from opsonization.

The bromoacetate moiety is an alternative to the maleimide group, reacting chemoselectively with free thiols at pH ≥8.0. It is useful for situations where the conjugate molecule needs to be kept at a high pH (≥8.0), above the range where maleimides can be used effectively, or in constructs where maleimide groups are unstable.

TFP esters are an alternate reactive group to the N-hydroxysuccinimidyl (NHS) ester and reacts with amines at an optimal pH range of 7.5 – 8.0, higher than the optimal range for NHS esters (pH 7.0 – 7.5). TFP esters are more hydrolytically stable than NHS esters, and they are more reactive toward amines in their optimal pH range than NHS esters are within the pH range 7.0 – 7.5.

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

Bromoacetamido-dPEG®4-TFP ester, product number QBD-11200, is a short (18 atoms, 20.4 Å), single molecular weight, discrete PEG (dPEG®) crosslinker functionalized with a thiol-reactive bromoacetate group on one end and an amine-reactive 2,3,5,6-tetrafluorophenyl (TFP) ester on the other.

The short, flexible, non-immunogenic dPEG® crosslinker increases the hydrodynamic volumes of conjugates in aqueous media, thereby increasing water solubility. The increased hydrodynamic volume can reduce or eliminate conjugate molecules’ renal clearance and shield conjugates from opsonization.

The bromoacetate moiety is an alternative to the maleimide group, reacting chemoselectively with free thiols at pH ≥8.0. It is useful for situations where the conjugate molecule needs to be kept at a high pH (≥8.0), above the range where maleimides can be used effectively, or in constructs where maleimide groups are unstable.

TFP esters are an alternate reactive group to N-hydroxysuccinimidyl (NHS) esters and react with amines at an optimal pH range of 7.5 – 8.0, higher than the optimal range for NHS esters (pH 7.0 – 7.5). TFP esters are more hydrolytically stable than NHS esters, and they are more reactive toward amines in their optimal pH range than NHS esters are within the pH range 7.0 – 7.5.

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

Bis-dPEG®7-NHS ester, product number QBD-10988, is a homobifunctional, amine-reactive, single molecular weight PEG crosslinker with a short (25 atoms, 28.6 Å) discrete PEG (dPEG®) chain length. Each end of the chain terminates as the N-hydroxysuccinimidyl (NHS) ester of propionic acid. Unlike traditional hydrophobic crosslinkers, Bis-dPEG®7-NHS ester will not cause problems such as aggregation, precipitation, and inactivation when conjugated to biomolecules. As a homobifunctional, amine-reactive crosslinker, the primary uses for QBD-10988 are intermolecular conjugation of biomolecules with free, surface-accessible amines and intramolecular modification of biomolecules using free, surface-accessible amines. Because QBD-10988 is one in a line of similar products, Bis-dPEG®7-NHS ester can be used with other products in the same line to probe the effect of different linker lengths on the performance of crosslinked or intramolecularly modified biomolecules.

NHS esters react with free amines such as the ε-amines of lysine. The optimal pH range for NHS esters to react with free amines is 7.0 – 7.5. However, NHS esters can react with free amines with pH as low as 6.5. NHS esters are susceptible to hydrolysis in aqueous media. As the pH increases, the hydrolysis rate of the ester increases. Thus, we strongly discourage storing Bis-dPEG®7-NHS ester 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. If customers desire to store the product in solution, we recommend the use of a pure, anhydrous, water-miscible solvent such as dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAC), or N,N-dimethylformamide (DMF). DMSO, DMAC, or DMF can be dried chemically or by storing for a minimum of 24 hours over 3 Å molecular sieves. With DMF, use only fresh solvent as the compound decomposes over time to form free amines that will react with the NHS esters.

Specifications

Documents

References

Inhibition of HLA-DQ2 Mediated Antigen Presentation by Analogues of a High Affinity 33-Residue Peptide from α2-Gliadin. Jiang Xia, Matthew Siegel, Elin Bergseng, Ludvig M. Sollid, and Chaitan Khosla. Journal of the American Chemical Society 2006 128 (6) pp 1859-1867 February 15, 2006. DOI:10.1021/ja056423o.