Reagent Kcleavagecocktail The dodt peptide cleavage process is a critical step in solid-phase peptide synthesis (SPPS), where the synthesized peptide is released from its solid support.The use of a lower percentage of TFA during thecleavagealong with thioether-based scavengers and reducing agents was more effective in mitigating Cys S- ... This is typically achieved using a cleavage cocktail, most commonly based on trifluoroacetic acid (TFA), which requires the addition of scavengers. One such important scavenger is 3,6-dioxa-1,8-octanedithiol, widely known by its acronym, DODT. DODT plays a crucial role in protecting sensitive amino acid residues within the peptide chain from degradation and unwanted side reactions during the acidic cleavage process. Understanding its function and how it's employed in various cleavage cocktails is essential for successful peptide synthesis and obtaining high-purity peptide products.
Peptide cleavage from the resin is a harsh process, primarily involving strong acids like TFA. These conditions can lead to various side reactions, especially with amino acids containing reactive side chains. DODT functions as a thiol scavenger, meaning it actively intercepts and neutralizes reactive species generated during cleavage.2,2 -(Ethylenedioxy)diethanethiol 95 14970-87-7 Its primary roles include:
* Scavenging Cations: During TFA cleavage, carbocations are generated, which can alkylate sensitive residues like methionine, cysteine, tryptophan, and tyrosineThe use of Dodt as a Non-Malodorous Scavenger in Fmoc .... DODT effectively traps these carbocations, preventing them from attacking the peptide chain.
* Suppressing Oxidation: DODT can also help suppress oxidative damage to vulnerable amino acids, particularly cysteine and methionine, which are prone to oxidation in the presence of reactive species.
* Non-Malodorous Alternative: Compared to other thiols like dithiothreitol (DTT) or mercaptoethanol, DODT is significantly less malodorous, making it a more user-friendly option in laboratory settings.
The effectiveness of DODT is often realized when used in combination with other reagents in a cleavage cocktail. The specific composition of these cocktails is tailored to the peptide's amino acid sequence and the protecting groups used during synthesis. Some common formulations and their components include:
* TFA/DODT/H2O/TIPS: This is a widely used mixtureThepeptidewas released from the resin by treating with. TFA/DODT/H2O/TIPS (94:2.5:2.5:1, v/v/v/v), to give crude cyclic precursor 10 (75 mg, 70% yield,66%.. Trifluoroacetic acid (TFA) is the primary cleavage agent. Triisopropylsilane (TIPS) is another important scavenger, particularly effective at reducing the formation of tert-butyl cations. Water is often included to aid solubility and control reaction rates.Application Note Peptide Cleavage and Protected ... The ratio of these components can vary, with some protocols suggesting a DODT cocktail is 90:5:5 (TFA:TIPS:DODT) or variations like 94:2.5:2.5:1 (TFA:DODT:H2O:TIPS).作者：K Neumann·被引用次数：75—For thepeptide cleavage, thepeptidewas treated with TFA/DODT/H2O (95:2.5:2.5, v/v) for 2 h and the resin was removed by filtration. The solution was ...
* TFA/DODT/Phenol/H2O/TIPS: For peptides containing tyrosine and tryptophan, phenol is often added to protect these residues from oxidation.
* TFA/DODT/Thioanisole: Thioanisole is another scavenger that can be used in conjunction with DODT, particularly for peptides with methionine residues.
The specific peptide cleavage mechanism involves the protonation of the linkage between the peptide and the resin, followed by nucleophilic attack by TFA or other components, leading to the release of the peptide. Scavengers like DODT are crucial for minimizing side reactions during this release.
While DODT is highly effective, it is not without potential complications.We have synthesized a random group ofpeptidesand performed cleavages using variouscleavagecocktails including 3,6-dioxa-1,8-octanedithiol (DODT). One significant concern is the possibility of alkylation by-products when using DODT, particularly in methionine-containing peptides. Research has indicated that DODT can sometimes lead to the formation of undesirable by-products, which can affect the purity of the final peptide. This highlights the importance of optimizing cleavage conditions and considering the specific amino acid composition of the peptideApplication Note Peptide Cleavage and Protected ....
Furthermore, the choice of scavenger and cleavage cocktail can impact sensitive residues. For instance, peptides containing cysteine require careful consideration of scavengers to prevent S-t-butylation or other side reactions. Learning which TFA-based mixtures and scavengers are best suited for a particular peptide is a key aspect of successful SPPS.1,8-octanedithiol (DODT) in Fmoc Solid-Phase Peptide ...
Ongoing research explores novel approaches to peptide cleavage, aiming for milder conditions, faster reaction times, and improved purity. Some systems, like CEM's elevated temperature cleavage system, offer simultaneous cleavage of multiple peptides, reducing the need for time-consuming manual processes.THE USE OF DODT AS A NON-MALODOROUS ... However, for many standard applications, representative protocols for peptide cleavage still rely on optimized TFA-based cocktails incorporating DODT.作者：A Teixeira·2002·被引用次数：49—Abstract: We have synthesized a random group ofpeptidesand performed cleavages using variouscleavagecocktails including 3,6-dioxa-1,8-octanedithiol ...
In summary, DODT is an indispensable reagent in peptide cleavage from resin, acting as a vital scavenger to protect sensitive amino acid residues. Its non-malodorous nature makes it a preferred choice over traditional thiols. While effective, understanding its potential side reactions and optimizing cocktail formulations based on peptide sequence and desired purity remains crucial for chemists engaged in peptide synthesis.
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