DODTpeptide cleavage Reagent K is a widely recognized and robust cleavage cocktail, particularly valuable in Fmoc-based solid-phase peptide synthesis (SPPS). Its primary function is to efficiently cleave synthesized peptides from the solid support and simultaneously remove side-chain protecting groups. This reagent is especially recommended for peptides containing sensitive amino acid residues such as cysteine (Cys), methionine (Met), tryptophan (Trp), and tyrosine (Tyr), where side reactions can be a significant concern during cleavage. The effective use of Reagent K, often a mixture of trifluoroacetic acid (TFA) with scavengers like water, phenol, thioanisole, and 1,2-ethanedithiol (EDT), is crucial for obtaining high-purity peptides.Peptide synthesis
The efficacy of Reagent K lies in its carefully balanced composition, which includes strong acids for cleavage and a combination of scavengers to mitigate undesirable side reactions2025年10月22日—... (Reagent K) was maximally efficient in inhibiting a great variety of side reactions. Synthesis and cleavage of 10 peptides, each containing .... Trifluoroacetic acid (TFA) serves as the primary cleavage agent, breaking the bond between the peptide and the resin, as well as removing acid-labile protecting groups from amino acid side chains.作者：DS King·1990·被引用次数：1021—Synthesis andcleavageof 10peptides, each containing 20-50 residues, demonstrated the complementarity of Fmoc chemistry withReagent Kfor efficient synthesis ... However, the reactive carbocations generated during this process can lead to alkylation of sensitive residues like Trp, Met, and Tyr.
To combat these issues, Reagent K incorporates various scavengers:
* Phenol: Helps to scavenge carbocations and can also be beneficial for cleaving peptides containing tyrosine.
* Thioanisole: Acts as a potent scavenger, effectively trapping carbocations and preventing alkylation.
* 1,2-Ethanedithiol (EDT): Particularly useful for protecting methionine and cysteine residues from oxidation and alkylation. It also helps to reduce disulfide bonds if they have formed prematurely.
* Water: While seemingly simple, water plays a role in the overall reaction kinetics and can help to modulate the reactivity of the TFA.
The specific ratio of these components in Reagent K, often cited as approximately 82.5% TFA, 5% water, 5% phenol, 5% thioanisole, and 2.5% EDT, has been optimized through extensive research to maximize cleavage efficiency while minimizing side-product formation2011年8月26日—All couplingreagentsand methods are applicable to the coupling of N- protected amino acids, but not all are applicable to the coupling of ....
Reagent K is a go-to choice for cleaving peptides that incorporate amino acids prone to side reactions during acidolysis. These include:
* Cysteine (Cys): Prone to forming disulfide bonds or undergoing S-alkylation.
* Methionine (Met): Susceptible to oxidation and alkylation.
* Tryptophan (Trp): Highly reactive towards electrophilic attack and carbocations.
* Tyrosine (Tyr): Can undergo electrophilic substitution.
When synthesizing peptides with multiple occurrences of these residues, the risk of forming truncated sequences, modified amino acids, or other impurities increases significantly2023年2月6日—Eachcleavagecocktail contains a unique combination of scavengers designed to prevent either side reactions mediated by the released protecting groups or the .... Reagent K, with its comprehensive scavenger system, is designed to effectively protect these sensitive sites, ensuring a cleaner crude peptide product. It is frequently employed as a standard cleavage mix, offering a reliable solution for many challenging peptide sequences.
While Reagent K is a highly effective and widely used cleavage cocktail, other reagents and strategies exist, and the optimal choice can depend on the specific peptide sequence and the synthesis protocolNovabiochem® - Fmoc resin cleavage protocols. For instance, "Reagent B" is mentioned as a cleavage cocktail for sensitive residues, and other specialized reagents exist for specific amino acids like methionine (e2025年7月15日—“Reagent K”is frequently used as standard cleavage mix, especially effective when Cys, Met, Trp or Tyr are present. Additionally it is ....g., "Reagent H").
The choice of resin also influences cleavage conditions. For example, peptides synthesized on 2-chlorotrityl chloride resin might require different cleavage reagents or protocols compared to those synthesized on Rink amide resin.Ultrafast Peptide Synthesis at Elevated Temperature Furthermore, the temperature and duration of cleavage can be critical factors.Produce a variety ofpeptidebonds with Spectrum's selection of tci organiccleavagework up agents fmoc solid phasepeptidesynthesis ... For peptides with multiple Arg(Pmc/Pbf) residues, longer cleavage times or specific adjustments to the cocktail might be necessary.
In some cases, modifications to the standard Reagent K composition may be beneficialProduce a variety ofpeptidebonds with Spectrum's selection of tci organiccleavagework up agents fmoc solid phasepeptidesynthesis .... For instance, using a lower percentage of TFA or adjusting the scavenger profile can help mitigate specific side reactions, such as the S-t-butylation of cysteine作者：DS KING·1990·被引用次数：1021—Synthesis andcleavageof 10peptides, each containing 20-50 residues, demonstrated the complementarity of Fmoc chemistry withReagent Kfor efficient synthesis .... Researchers often adapt these cocktails based on their experimental observations and the unique challenges presented by their target peptides.
Reagent K stands as a cornerstone in peptide cleavage protocols, particularly within the Fmoc-SPPS frameworkCys(Trt)/Met/Trp-rich: useReagent Kor H (EDT + thioanisole + phenol), maintain 0–5 °C, handle in sealed vessel. Tyr-containing sequences: include ≤ 2 % phenol .... Its carefully formulated blend of TFA and scavengers provides robust protection against side reactions, making it an indispensable tool for cleaving peptides containing sensitive amino acid residues. By understanding its composition and application, researchers can significantly improve the yield and purity of their synthesized peptides, paving the way for more successful downstream applicationsGuide to Solid Phase Peptide Synthesis - AAPPTEC.
Join the newsletter to receive news, updates, new products and freebies in your inbox.