Peptide Synthesis Strategy: Using Fmoc-O-tert-butyl-L-serine Efficiently
Mastering peptide synthesis requires a deep understanding of the reagents used and the strategic application of protective groups. Fmoc-O-tert-butyl-L-serine is a vital amino acid derivative in Fmoc-based solid-phase peptide synthesis (SPPS), and its efficient use is key to producing high-quality peptides. NINGBO INNO PHARMCHEM CO.,LTD., a leading manufacturer of peptide synthesis reagents in China, shares insights into optimizing its application.
Fmoc-O-tert-butyl-L-serine (CAS: 71989-33-8) provides a protected serine residue that can be sequentially incorporated into a growing peptide chain. The core of its efficient use lies in understanding the two protective groups:
1. Fmoc Group (N-terminal): This group is removed by mild bases, commonly piperidine (typically 20-50% in DMF), which regenerates the free N-terminal amine for the next amino acid coupling. The deprotection step should be monitored (e.g., by UV absorbance of the dibenzofulvene adduct) to ensure complete removal without degrading the growing peptide chain.
2. tert-Butyl Group (Side Chain): This acid-labile group protects the serine hydroxyl. It is generally removed during the final cleavage of the peptide from the resin. Efficient cleavage requires a strong acid cocktail, most commonly trifluoroacetic acid (TFA), often in the presence of scavengers like triisopropylsilane (TIS), water, or ethanedithiol (EDT) to capture reactive carbocations generated from the protecting groups and prevent side reactions with sensitive amino acids.
Efficient Strategies for Using Fmoc-O-tert-butyl-L-serine:
1. Coupling Optimization:
* Reagents: Use proven coupling reagents such as HBTU/HOBt, HATU, or DIC/HOBt. The choice can depend on the specific amino acid sequence and any steric hindrance.
* Solvent: N,N-Dimethylformamide (DMF) or N-Methyl-2-pyrrolidone (NMP) are standard solvents. Ensure adequate dissolution of the Fmoc-amino acid derivative before coupling.
* Activation Time: Allow sufficient activation time for the coupling reagents to react with the carboxyl group of Fmoc-O-tert-butyl-L-serine before adding it to the resin-bound peptide.
* Double Coupling: For difficult couplings (e.g., sterically hindered amino acids or aggregation-prone sequences), a double coupling step or using a more potent coupling agent might be necessary.
2. Fmoc Deprotection:
* Piperidine Concentration: While 20% piperidine in DMF is common, the optimal concentration might vary. Higher concentrations can speed up deprotection but may also increase the risk of side reactions.
* Reaction Time: Typically, 5-10 minutes for primary amines and slightly longer for secondary amines. Two sequential deprotection steps are standard.
* Washing: Thorough washing with DMF after deprotection is crucial to remove piperidine and the dibenzofulvene adduct, preventing these from interfering with subsequent coupling.
3. Final Cleavage and Deprotection:
* Acid Cocktail: A typical cleavage cocktail is 95% TFA with 5% scavengers. The scavengers are crucial for amino acids with acid-labile side chains, including the tert-butyl group on serine. Adjusting scavenger ratios might be needed based on the peptide sequence.
* Reaction Time: Cleavage usually takes 1-4 hours at room temperature.
* Precipitation: After cleavage, the peptide is typically precipitated by adding cold diethyl ether. This removes the acid and scavengers, leaving the crude peptide.
4. Purification:
* Following precipitation, RP-HPLC is the standard method for purifying synthetic peptides, yielding the desired product with high purity. If you plan to buy Fmoc-O-tert-butyl-L-serine, consider purchasing from NINGBO INNO PHARMCHEM CO.,LTD. to ensure you have a reliable starting material for these optimized processes.
Efficiently utilizing Fmoc-O-tert-butyl-L-serine means understanding its chemistry and applying optimized protocols for each step of the synthesis. By partnering with reputable suppliers like NINGBO INNO PHARMCHEM CO.,LTD., you secure high-quality reagents that are foundational to successful peptide production.
Fmoc-O-tert-butyl-L-serine (CAS: 71989-33-8) provides a protected serine residue that can be sequentially incorporated into a growing peptide chain. The core of its efficient use lies in understanding the two protective groups:
1. Fmoc Group (N-terminal): This group is removed by mild bases, commonly piperidine (typically 20-50% in DMF), which regenerates the free N-terminal amine for the next amino acid coupling. The deprotection step should be monitored (e.g., by UV absorbance of the dibenzofulvene adduct) to ensure complete removal without degrading the growing peptide chain.
2. tert-Butyl Group (Side Chain): This acid-labile group protects the serine hydroxyl. It is generally removed during the final cleavage of the peptide from the resin. Efficient cleavage requires a strong acid cocktail, most commonly trifluoroacetic acid (TFA), often in the presence of scavengers like triisopropylsilane (TIS), water, or ethanedithiol (EDT) to capture reactive carbocations generated from the protecting groups and prevent side reactions with sensitive amino acids.
Efficient Strategies for Using Fmoc-O-tert-butyl-L-serine:
1. Coupling Optimization:
* Reagents: Use proven coupling reagents such as HBTU/HOBt, HATU, or DIC/HOBt. The choice can depend on the specific amino acid sequence and any steric hindrance.
* Solvent: N,N-Dimethylformamide (DMF) or N-Methyl-2-pyrrolidone (NMP) are standard solvents. Ensure adequate dissolution of the Fmoc-amino acid derivative before coupling.
* Activation Time: Allow sufficient activation time for the coupling reagents to react with the carboxyl group of Fmoc-O-tert-butyl-L-serine before adding it to the resin-bound peptide.
* Double Coupling: For difficult couplings (e.g., sterically hindered amino acids or aggregation-prone sequences), a double coupling step or using a more potent coupling agent might be necessary.
2. Fmoc Deprotection:
* Piperidine Concentration: While 20% piperidine in DMF is common, the optimal concentration might vary. Higher concentrations can speed up deprotection but may also increase the risk of side reactions.
* Reaction Time: Typically, 5-10 minutes for primary amines and slightly longer for secondary amines. Two sequential deprotection steps are standard.
* Washing: Thorough washing with DMF after deprotection is crucial to remove piperidine and the dibenzofulvene adduct, preventing these from interfering with subsequent coupling.
3. Final Cleavage and Deprotection:
* Acid Cocktail: A typical cleavage cocktail is 95% TFA with 5% scavengers. The scavengers are crucial for amino acids with acid-labile side chains, including the tert-butyl group on serine. Adjusting scavenger ratios might be needed based on the peptide sequence.
* Reaction Time: Cleavage usually takes 1-4 hours at room temperature.
* Precipitation: After cleavage, the peptide is typically precipitated by adding cold diethyl ether. This removes the acid and scavengers, leaving the crude peptide.
4. Purification:
* Following precipitation, RP-HPLC is the standard method for purifying synthetic peptides, yielding the desired product with high purity. If you plan to buy Fmoc-O-tert-butyl-L-serine, consider purchasing from NINGBO INNO PHARMCHEM CO.,LTD. to ensure you have a reliable starting material for these optimized processes.
Efficiently utilizing Fmoc-O-tert-butyl-L-serine means understanding its chemistry and applying optimized protocols for each step of the synthesis. By partnering with reputable suppliers like NINGBO INNO PHARMCHEM CO.,LTD., you secure high-quality reagents that are foundational to successful peptide production.
Perspectives & Insights
Alpha Spark Labs
“, by UV absorbance of the dibenzofulvene adduct) to ensure complete removal without degrading the growing peptide chain.”
Future Pioneer 88
“tert-Butyl Group (Side Chain): This acid-labile group protects the serine hydroxyl.”
Core Explorer Pro
“Coupling Optimization:* Reagents: Use proven coupling reagents such as HBTU/HOBt, HATU, or DIC/HOBt.”