Conjugation of salmon calcitonin to a combed-shaped end functionalized poly(poly(ethylene glycol) methyl ether methacrylate) yields a bioactive stable conjugate

Ryan, Sinéad M.; Wang, Xuexuan; Mantovani, Giuseppe; Sayers, Claire T.; Haddleton, David M.; Brayden, David J.

doi:10.1016/j.jconrel.2008.12.014

Cited by 75 publications

(71 citation statements)

References 39 publications

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“…injection of PBS were without effect on plasma calcium levels. 22 Homeostatic events mean that plasma calcium levels do not move from 2.5 mM in untreated conditions. Figure 8.…”

Section: Characterization Of Sct-polymer Conjugates: Attachment Sitementioning

confidence: 99%

Direct Peptide Bioconjugation/PEGylation at Tyrosine with Linear and Branched Polymeric Diazonium Salts

et al. 2012

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Direct polymer conjugation at peptide tyrosine residues is described. In this study Tyr residues of both leucine enkephalin and salmon calcitonin (sCT) were targeted using appropriate diazonium salt-terminated linear monomethoxy poly(ethylene glycol)s (mPEGs) and poly(mPEG) methacrylate prepared by atom transfer radical polymerization. Judicious choice of the reaction conditionspH, stoichiometry, and chemical structure of diazonium saltled to a high degree of site-specificity in the conjugation reaction, even in the presence of competitive peptide amino acid targets such as histidine, lysines, and N-terminal amine. In vitro studies showed that conjugation of mPEG2000 to sCT did not affect the peptide’s ability to increase intracellular cAMP induced in T47D human breast cancer cells bearing sCT receptors. Preliminary in vivo investigation showed preserved ability to reduce [Ca2+] plasma levels by mPEG2000-sCT conjugate in rat animal models.

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“…injection of PBS were without effect on plasma calcium levels. 22 Homeostatic events mean that plasma calcium levels do not move from 2.5 mM in untreated conditions. Figure 8.…”

Section: Characterization Of Sct-polymer Conjugates: Attachment Sitementioning

confidence: 99%

Direct Peptide Bioconjugation/PEGylation at Tyrosine with Linear and Branched Polymeric Diazonium Salts

et al. 2012

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“…We recently demonstrated specific cysteine-1 conjugation of sCT to a combedshaped end-functionalised poly(PEG-methyl ether methacrylate) comb-shaped polymer, (sCT-P) [11]. The 6.5 kDa MW conjugate had increased proteolytic stability compared to both free sCT and a linear PEG version of similar total MW.…”

Section: Introductionmentioning

confidence: 99%

“…The 6.5 kDa MW conjugate had increased proteolytic stability compared to both free sCT and a linear PEG version of similar total MW. In addition to lengthening the half-life of sCT following injection to rats, in vitro and in vivo efficacy and potency was retained by the conjugate [11]. The aim of the present study was to evaluate the effects of increasing the MW of the comb-shaped polymer conjugated onto sCT on both in vitro bioactivity and in vivo PK following i.v.…”

Section: Introductionmentioning

confidence: 99%

PK/PD modelling of comb-shaped PEGylated salmon calcitonin conjugates of differing molecular weights

Ryan

Frías²,

Wang

et al. 2011

Journal of Controlled Release

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Salmon calcitonin (sCT) was conjugated via cysteine-1 to novel combed-shaped endfunctionalised poly(PEG) methyl ether methacrylate) (sCT-P) comb-shaped polymers, to yield conjugates of total molecular weights (MW) inclusive of sCT: 6.5, 9.5, 23 and 40 kDa. The conjugates were characterised by HPLC and their in vitro and in vivo bioactivity was measured by cAMP assay on human T47D cells and following intravenous (i.v.) injection to rats, respectively. Stability against endopeptidases, rat serum and liver homogenates was assessed. There were linear and exponential relationships between conjugate MW with potency and efficacy respectively, however the largest MW conjugate still retained 70% of E max and an EC 50 of 3.7 nM. In vivo, while free sCT and the conjugates reduced serum [calcium] to a maximum of 15-30 % over 240 min, the half life (T½) was increased and the area under the curve (AUC) was extended in proportion to conjugate MW. Likewise, the polymer conferred protection on sCT against attack by trypsin, chymotrypsin, elastase, rat serum and liver homogenates, with the best protection afforded by sCT-P (40 kDa). Mathematical modelling accurately predicted the MW relationships to in vitro efficacy, potency, in vivo PK and enzymatic stability. With a significant increase in T½ for sCT, the 40 kDa MW comb-shaped PEG conjugate of sCT may have potential as a long-acting injectable formulation.

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Section: Introductionmentioning

confidence: 99%

“…[6,17,18] Recently, comb-like PEG polymers, i.e., polyethylene glycol grafted poly(meth)acrylates, have proved to be potent alternatives to linear and branched PEG for improving the pharmacokinetics of protein drugs. [18][19][20] When compared to the linear PEG with equivalent molecular weights, the comb-like PEG displays greater steric hindrance, thus potentially enhancing biostability and lowering clearance rates of the conjugated biotherapeutics. Moreover, comb-shaped PEG-(meth)acrylate polymers can be prepared by reversible addition fragmentation chain transfer (RAFT) polymerization [21][22][23][24][25] and atom transfer radical polymerization (ATRP) techniques, [26][27][28][29] which offer facile synthetic routes to the generation of polymers with controlled molecular weight, varying macromolecular architectures and defined endgroup functionalities.…”

Section: Introductionmentioning

confidence: 99%

Conjugation of siRNA with Comb‐Type PEG Enhances Serum Stability and Gene Silencing Efficiency

Gunasekaran

Nguyen

Maynard

et al. 2011

Macromol. Rapid Commun.

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A thiol‐modified siRNA targeting the enhanced green fluorescence protein (eGFP) gene was conjugated with RAFT‐synthesized, pyridyl disulfide‐functional poly(PEG methyl ether acrylate)s (p(PEGA)s). siRNA‐p(PEGA) conjugates demonstrated significantly enhanced in vitro serum stability and nuclease resistance compared to the unmodified and thiol‐modified siRNA. The complexes of siRNA‐p(PEGA) conjugates with a fusogenic peptide, KALA ((+)/(–) = 2) inhibited the protein expression approximately 28‐fold more than the KALA complex of the unmodified siRNA. The protein inhibition caused by siRNA‐p(PEGA)‐KALA complexes (56 ± 5%–58 ± 3% of the fluorescence expressed in non‐treated cells) was comparable to the effect of the unmodified siRNA‐lipofectamine complex (77 ± 7%). magnified image

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Conjugation of salmon calcitonin to a combed-shaped end functionalized poly(poly(ethylene glycol) methyl ether methacrylate) yields a bioactive stable conjugate

Cited by 75 publications

References 39 publications

Direct Peptide Bioconjugation/PEGylation at Tyrosine with Linear and Branched Polymeric Diazonium Salts

Direct Peptide Bioconjugation/PEGylation at Tyrosine with Linear and Branched Polymeric Diazonium Salts

PK/PD modelling of comb-shaped PEGylated salmon calcitonin conjugates of differing molecular weights

Conjugation of siRNA with Comb‐Type PEG Enhances Serum Stability and Gene Silencing Efficiency

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