what-is-a-poly-peptide The total chemical synthesis of complex natural products like nisin presents a significant challenge, often necessitating advanced techniques such as solid-phase peptide synthesis (SPPS)作者：R Dickman·2018—This thesis describes thesynthesisand structural analysis of the target-binding region ofnisinand its close structural relative mutacin I. The lantibiotics .... Nisin, a lantibiotic, is characterized by its highly modified structure, including unusual amino acids and thioether bridges, which complicates its laboratory production compared to simpler peptides.Unparalleled Solid Phase Peptide Peptide Synthesis This article delves into the intricacies of synthesizing nisin and its analogues, primarily focusing on the application of solid-phase peptide synthesis as a primary methodology.
Nisin is a bacteriocin produced by *Lactococcus lactis* that functions as an antibiotic by targeting lipid II, a crucial precursor in bacterial cell wall biosynthesis. Its structure is notable for containing lanthionine and methyllanthionine residues, which are formed through post-translational modifications of cysteine and dehydroalanine/dehydrobutyrine residues. These unique structural features, along with its oxidative instability, make its *de novo* chemical synthesis a formidable task. Traditional solution-phase synthesis methods are often impractical for such complex molecules, leading researchers to explore more robust and efficient strategies.
Solid-phase peptide synthesis has emerged as a cornerstone technique for constructing peptides, including complex ones like nisin and its derivatives.6QM1: Solution NMR of synthetic analogues of nisin and ... The fundamental principle of SPPS involves anchoring the C-terminal amino acid to an insoluble polymer support (resin) and sequentially adding amino acids to the growing peptide chain...totalstepwisesolid phase peptide synthesisled to the successful preparation of an analogue of the model peptide, insulin-like peptide 3 (INSL3), in which .... Each coupling step is followed by a deprotection step, allowing the next amino acid to be attachedRing-opening reactions for the solid-phase synthesis of ....
The advantages of SPPS for nisin synthesis and analogue development are numerous:
* Simplified Purification: Excess reagents and byproducts are easily washed away with the resin, drastically simplifying the purification process compared to solution-phase methods.
* Efficiency: The sequential nature of SPPS allows for high yields and purity if coupling and deprotection steps are optimized.
* Automation: SPPS is amenable to automation, which can increase throughput and reproducibility.
* Analogue Design: SPPS facilitates the creation of modified nisin structures by allowing for the incorporation of non-natural amino acids or altered peptide sequences, crucial for structure-activity relationship studies.
Researchers have successfully employed SPPS to synthesize various fragments of nisin, such as individual ring structures (e作者：R Dickman·2018—This thesis describes thesynthesisand structural analysis of the target-binding region ofnisinand its close structural relative mutacin I. The lantibiotics ....g.作者：R Dickman·2019·被引用次数：26—We have usedsolid-phase peptide synthesisto prepare two novel analogues ofnisin(1–12) in which the dehydro residues have been replaced., ring A and ring B), and complete analogues with modifications. For instance, studies have focused on creating analogues where dehydro residues are replaced or where thioamide linkages are introduced, using techniques like Fmoc-based SPPS, which utilizes the fluorenylmethyloxycarbonyl (Fmoc) protecting group. Microwave-assisted SPPS has also been utilized to accelerate coupling reactions, which is particularly beneficial for overcoming the challenging couplings often encountered in the synthesis of modified peptides.
Despite the power of SPPS, synthesizing a molecule as intricate as nisin is not without its hurdles. The formation of thioether bridges, the presence of unusual amino acids, and the potential for epimerization during coupling require specialized reagents and meticulous optimization of reaction conditions.
Innovations in SPPS continue to address these challenges:
* Resin Choice: Selecting the appropriate resin and linker is critical for efficient anchoring and cleavage of the final peptide.
* Coupling Reagents: Advanced coupling reagents are employed to ensure efficient peptide bond formation while minimizing side reactionsThe more acidic coupling environment with carbodiimidechemistryovercomes coupling issues for cysteine. (epimerization) and arginine (γ-lactam formation), ....
* Protecting Group Strategies: Orthogonal protecting groups are essential to selectively deprotect amino acid side chains at appropriate stages of the synthesis作者：R Dickman·2019·被引用次数：26—We have usedsolid-phase peptide synthesisto prepare two novel analogues ofnisin(1–12) in which the dehydro residues have been replaced..
* On-Resin Modifications: Some synthetic strategies involve performing modifications, such as the formation of thioether bridges, directly on the resin-bound peptide, which can streamline the overall process.
The total chemical synthesis of nisin remains an active area of research, pushing the boundaries of peptide chemistry.The purpose of this guide is to provide practical information for planning and executing successfulsolid phase peptidesyntheses. The ability to synthesize nisin and its analogues through SPPS not only aids in understanding its biological mechanism of action, particularly its interaction with Lipid II, but also opens avenues for developing novel antimicrobial agents. The ongoing advancements in peptide chemistry and solid-phase peptide synthesis continue to make the laboratory production of such complex natural products more feasible and accessible.
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