An amine-derivatized, DOTA-loaded polymeric support for Fmoc Solid Phase Peptide Synthesis.
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PROVIDER: S-EPMC2702766 | BioStudies |
REPOSITORIES: biostudies
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Project description:We have systematically explored three approaches based on 9-fluorenylmethoxycarbonyl (Fmoc) chemistry solid phase peptide synthesis (SPPS) for the total chemical synthesis of the key depsipeptide intermediate for the efficient total chemical synthesis of insulin. The approaches used were: stepwise Fmoc chemistry SPPS; the "hybrid method", in which maximally protected peptide segments made by Fmoc chemistry SPPS are condensed in solution; and, native chemical ligation using peptide-thioester segments generated by Fmoc chemistry SPPS. A key building block in all three approaches was a Glu[O-?-(Thr)] ester-linked dipeptide equipped with a set of orthogonal protecting groups compatible with Fmoc chemistry SPPS. The most effective method for the preparation of the 51 residue ester-linked polypeptide chain of ester insulin was the use of unprotected peptide-thioester segments, prepared from peptide-hydrazides synthesized by Fmoc chemistry SPPS, and condensed by native chemical ligation. High-resolution X-ray crystallography confirmed the disulfide pairings and three-dimensional structure of synthetic insulin lispro prepared from ester insulin lispro by this route. Further optimization of these pilot studies could yield an efficient total chemical synthesis of insulin lispro (Humalog) based on peptide synthesis by Fmoc chemistry SPPS.
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Project description:We report here the synthesis of the first selenocysteine SPPS derivatives which bear TFA-labile sidechain protecting groups. New compounds Fmoc-Sec(Xan)-OH and Fmoc-Sec(Trt)-OH are presented as useful and practical alternatives to the traditional Fmoc-Sec-OH derivatives currently available to the peptide chemist. From a bis Fmoc-protected selenocystine precursor, multiple avenues of diselenide reduction were attempted to determine the most effective method for subsequent attachment of the protecting group electrophiles. Our previously reported one-pot reduction methodology was ultimately chosen as the optimal approach toward the synthesis of these novel building blocks, and both were easily obtained in high yield and purity. Fmoc-Sec(Xan)-OH was discovered to be bench-stable for extended timeframes while the corresponding Fmoc-Sec(Trt)-OH derivative appeared to detritylate slowly when not stored at -20?°C. Both Sec derivatives were incorporated into single- and multiple-Sec-containing test peptides in order to ascertain the peptides' deprotection behavior and final form upon TFA cleavage. Single-Sec-containing test peptides were always isolated as their corresponding diselenide dimers, while dual-Sec-containing peptide sequences were afforded exclusively as their intramolecular diselenides.
| S-EPMC5538775 | BioStudies
Project description:Syntheses of Fmoc amino acids having zinc-binding groups were prepared and incorporated into substrate inhibitor H3K27 peptides using Fmoc/<sup>t</sup>Bu solid-phase peptide synthesis (SPPS). Peptide 11, prepared using Fmoc-Asu(NHO<sup>t</sup>Bu)-OH, is a potent inhibitor (IC<sub>50</sub> = 390 nM) of the core NuRD corepressor complex (HDAC1-MTA1-RBBP4). The Fmoc amino acids have the potential to facilitate the rapid preparation of substrate peptidomimetic inhibitor (SPI) libraries in the search for selective HDAC inhibitors.
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Project description:Peptide-based hydrogels (PHGs) are biocompatible materials suitable for biological, biomedical, and biotechnological applications, such as drug delivery and diagnostic tools for imaging. Recently, a novel class of synthetic hydrogel-forming amphiphilic cationic peptides (referred to as series K), containing an aliphatic region and a Lys residue, was proposed as a scaffold for bioprinting applications. Here, we report the synthesis of six analogues of the series K, in which the acetyl group at the N-terminus is replaced by aromatic portions, such as the Fmoc protecting group or the Fmoc-FF hydrogelator. The tendency of all peptides to self-assemble and to gel in aqueous solution was investigated using a set of biophysical techniques. The structural characterization pointed out that only the Fmoc-derivatives of series K keep their capability to gel. Among them, Fmoc-K3 hydrogel, which is the more rigid one (G' = 2526 Pa), acts as potential material for tissue engineering, fully supporting cell adhesion, survival, and duplication. These results describe a gelification process, allowed only by the correct balancing among aggregation forces within the peptide sequences (e.g., van der Waals, hydrogen bonding, and π-π stacking).
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Project description:In this report we directly compare the in vivo and in vitro MRI properties of gadolinium-dendrimer conjugates of derivatized acyclic diethylenetriamine-N,N',N',N'',N''-pentaacetic acid (1B4M-DTPA) and macrocyclic 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (C-DOTA). The metal-ligand chelates were pre-formed in alcohol prior to conjugation to the generation 4 PAMAM dendrimer (G4D), and the dendrimer-based agents were purified by Sephadex(R) G-25 column. The analysis and SE-HPLC data indicated chelate to dendrimer ratios of 30:1 and 28:1, respectively. Molar relaxivity measured at pH 7.4, 22 degrees C, and 3T are comparable (29.5 vs 26.9 mM(-1)s(-1)), and both conjugates are equally viable as MRI contrast agents based on the images obtained. The macrocyclic agent however exhibits a faster rate of clearance in vivo (t(1/2)=16 vs 29 min). Our conclusion is that the macrocyclic-based agent is the more suitable agent for in vivo use for these reasons combined with kinetic inertness associated with the Gd(III) DOTA complex stability properties.
| S-EPMC2918719 | BioStudies
Project description:C-terminal peptide thioesters are an essential component of the native chemical ligation approach for the preparation of fully or semisynthetic proteins. However, the efficient generation of C-terminal thioesters by Fmoc solid-phase peptide synthesis remains a challenge. The recent N-acylurea approach to thioester synthesis relies on the deactivation of one amine of 3,4-diaminobenzoic acid (Dbz) during Fmoc SPPS. Here, we demonstrate that this approach results in the formation of side products through the over-acylation of Dbz, particularly when applied to Gly-rich sequences. We find that orthogonal allyloxycarbonyl (Alloc) protection of a single Dbz amine eliminates these side products. We introduce a protected Fmoc-Dbz(Alloc) base resin that may be directly used for synthesis with most C-terminal amino acids. Following synthesis, quantitative removal of the Alloc group allows conversion to the active N-acyl-benzimidazolinone (Nbz) species, which can be purified and converted in situ to thioester under ligation conditions. This method is compatible with the automated preparation of peptide-Nbz conjugates. We demonstrate that Dbz protection improves the synthetic purity of Gly-rich peptide sequences derived from histone H4, as well as a 44-residue peptide from histone H3.
2011-01-01 | S-EPMC3558277 | BioStudies
Project description:Thioether containing peptides were obtained following three synthetic routes. In route A, halo acids esterified on 2-chlorotrityl(Cltr) resin were reacted with N-fluorenylmethoxycarbonyl (Fmoc) aminothiols. These were either cleaved from the resin to the corresponding (Fmoc-aminothiol)carboxylic acids, which were used as key building blocks in solid phase peptide synthesis (SPPS), or the N-Fmoc group was deprotected and peptide chains were elongated by standard SPPS. The obtained N-Fmoc protected thioether containing peptides were then condensed either in solution, or on solid support, with the appropriate amino components of peptides. In route B, the thioether containing peptides were obtained by the reaction of N-Fmoc aminothiols with bromoacetylated peptides, which were synthesized on Cltr-resin, followed by removal of the N-Fmoc group and subsequent peptide elongation by standard SPPS. In route C, the thioether containing peptides were obtained by the condensation of a haloacylated peptide synthesized on Cltr-resin and a thiol-peptide synthesized either on 4-methoxytrityl(Mmt) or trityl(Trt) resin.
| S-EPMC6983143 | BioStudies
Project description:LnDOTA-tetraamide chelates (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) have received considerable recent attention as a result of their potential to act as PARACEST contrast agents for magnetic resonance imaging (MRI). Although PARACEST agents afford several advantages over conventional contrast agents they suffer from substantially higher detection limits; thus, improving the effectiveness of LnDOTA-tetraamide chelates is an important goal. In this study we investigate the potential to extend conformational control of LnDOTA-type ligands to those applicable to PARACEST. Furthermore, the question of whether ?- rather than ?-substitution of the pendant arms could be used to control the chelate coordination geometry is addressed. Although ?-substitution does influence coordination geometry it does not afford control. However, it can play an important role in governing the conformation of the amide substituent relative to the chelate in such as way that suggests a PARACEST agent could be designed that has detection limits at least as low as a conventional MRI contrast agent.
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Project description:To combat the escalating rise of antibacterial resistance, the development of antimicrobial peptides (AMPs) with a unique mode of action is considered an attractive strategy. However, proteolytic degradation of AMPs remains the greatest challenge in their transformation into therapeutics. Herein, we synthesized Fmoc-triazine amino acids that differ from each other by anchoring either cationic or hydrophobic residues. These unnatural amino acids were adopted for solid-phase peptide synthesis (SPPS) to synthesize a series of amphipathic antimicrobial peptidomimetics. From the antimicrobial screening, we found that the trimer, BJK-4 is the most potent short antimicrobial peptidomimetic without showing hemolytic activity and it displayed enhanced proteolytic stability. Moreover, the mechanism of action to kill bacteria was found to be an intracellular targeting.
| S-EPMC7279249 | BioStudies
Project description:We report an operationally simple method to facilitate chemical protein synthesis by fully convergent and one-pot native chemical ligations utilizing the fluorenylmethyloxycarbonyl (Fmoc) moiety as an N-masking group of the N-terminal cysteine of the middle peptide thioester segment(s). The Fmoc group is stable to the harsh oxidative conditions frequently used to generate peptide thioesters from peptide hydrazide or o-aminoanilide. The ready availability of Fmoc-Cys(Trt)-OH, which is routinely used in Fmoc solid-phase peptide synthesis, where the Fmoc group is pre-installed on cysteine residue, minimizes additional steps required for the temporary protection of the N-terminal cysteinyl peptides. The Fmoc group is readily removed after ligation by short exposure (<7?min) to 20?% piperidine at pH?11 in aqueous conditions at room temperature. Subsequent native chemical ligation reactions can be performed in presence of piperidine in the same solution at pH?7.
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