Fast conventional Fmoc solid‐phase peptide synthesis with HCTU

Abstract

1H-Benzotriazolium 1-[bis(dimethyl-amino)methylene]-5-chloro-hexafluorophosphate (1-),3-oxide (HCTU) is a nontoxic, nonirritating and noncorrosive coupling reagent. Seven biologically active peptides (GHRP-6, 65 -74 ACP, oxytocin, G-LHRH, Cpeptide, hAmylin 1 -37 , and β-amyloid 1 -42 ) were synthesized with reaction times reduced to deprotection times of 3 min or less and coupling times of 5 min or less using HCTU as the coupling reagent. Expensive coupling reagents or special techniques were not used. Total peptide synthesis times were dramatically reduced by as much as 42.5 h (1.8 days) without reducing the crude peptide purities. It was shown that HCTU can be used as an affordable, efficient coupling reagent for fast Fmoc solid-phase peptide synthesis.

Multivalent Viral Capsids with Internal Cargo for Fibrin Imaging

“…A GPR peptide bearing an o -aminophenol for coupling to MS2 was prepared using solid phase peptide synthesis (Figure 1b) [48]. The sequence Gly-Gly-Ser-Lys-Gly-Tyr was added to the peptide to increase the spacing between the binding residues and the capsid, as well as provide a functional handle for modification (Tyr).…”

“…The aniline functionality was introduced onto the exterior surface of the capsids using the amber stop codon suppression method developed by the Schultz group [49], [50]. The o -aminophenol functionality was then incorporated into the peptide targeting group by chemically modifying a tyrosine residue after synthesis on the solid phase using standard Fmoc chemistry [48]. Removal of the side-chain protecting groups, azo coupling, and subsequent reduction with Na 2 S 2 O 4 afforded the desired o -aminophenol-containing peptides (Figure 1c).…”

“…Deprotection of the Fmoc groups was performed with a 20 min incubation in a 20% v/v piperidine in dimethylformamide (DMF) solution. Coupling reactions were carried out using 20 equivalents of amino acid with 10 equivalents of 2-(6-chloro-1- H -benzotriazole-1-yl)-1,1,3,3-tetramethylaminium hexafluorophosphate (HCTU) [48] and 20 equivalents of N , N -diisopropylethylamine (DIPEA) in DMF for 20 min. Side-chain deprotection was accomplished using a 1–2 h incubation with either a 95∶2.5∶2.5 ratio of TFA to H 2 O to triisopropylsilane (TIPS) (peptides without cysteine) or a 90∶5∶2.5∶2.5 ratio of TFA to phenol to H 2 O to TIPS (peptides containing cysteine).…”

Highly efficient and fast pre-activation cyclization of the long peptide: Succinimidyl ester-amine reaction revisited

“…At present, carboxyl activation by NHS ester formation is no longer the primary method of amide formation in peptide synthesis due to the advent of more efficient in situ carboxyl activation reagents, such as various uronium and phosphonium salts. [23][24][25] However, the NHS method is probably the most frequently used method for bioconjugation. 26 Compounds activated with NHS esters can be isolated and stored for long periods, which is why many compounds are commercially available in NHS ester-activated forms.…”

Chemical Strategies for Controlling Protein Folding and Elucidating the Molecular Mechanisms of Amyloid Formation and Toxicity

“…201103032/abstract prepared using SPPS. 5,82,83 However, the synthesis, purification, and handling of many of these amyloidforming peptides (e.g., Aβ and IAPP) are often plagued by protein aggregation and still present many challenges. The polyQ stretch of the Huntingtin protein is especially difficult to synthesize and purify.…”