Product Name: Ac-pSar16-OH
Sequence: Ac-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-Sar-OH
Chemical Formula: C50H84N16O18
Molar Mass: 1197.30
Purity: 95%
Storage : Sealed storage, away from moisture
SMILES: CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)N(C)CC(=O)O
IUPACNAME: 2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[[2-[acetyl(methyl)amino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetyl]-methylamino]acetic acid
INCHIKEY: XPMSKJZBUWLZKW-UHFFFAOYSA-N
INCHI: InChI=1S/C50H84N16O18/c1-34(67)51(2)18-35(68)52(3)19-36(69)53(4)20-37(70)54(5)21-38(71)55(6)22-39(72)56(7)23-40(73)57(8)24-41(74)58(9)25-42(75)59(10)26-43(76)60(11)27-44(77)61(12)28-45(78)62(13)29-46(79)63(14)30-47(80)64(15)31-48(81)65(16)32-49(82)66(17)33-50(83)84/h18-33H2,1-17H3,(H,83,84)
Application: Ac-pSar16-OH is a polysarcosine-based hydrophilic polymer that can serve as an alternative to PEG in therapeutic protein conjugation research. Composed of sarcosine repeat units, Ac-pSar16-OH offers water solubility, flexibility, and biocompatibility, making it useful for improving the physicochemical properties of protein and peptide conjugates. Compared with PEG-based linkers, polysarcosine materials are increasingly studied for reduced immunogenicity concerns and controlled conjugation design. Ac-pSar16-OH is valuable for drug delivery research, protein modification, peptide synthesis, bioconjugation, and development of next-generation therapeutic protein conjugates requiring hydrophilic, PEG-alternative linker systems.
Current Research: Overview Ac-pSar16-OH is a short polysarcosine (pSar) oligomer that can be used as a PEG alternative in therapeutic protein conjugation research. Polysarcosine is a hydrophilic, nonionic polypeptoid based on sarcosine, also known as N-methylglycine. Product references describe Ac-pSar16-OH as a polysarcosine reagent that can replace PEG for therapeutic protein conjugation. Its reported molecular formula is C50H84N16O18, with a molecular weight of 1197.30. Protein conjugation is an important strategy in modern biopharmaceutical development. Many therapeutic proteins and peptides have short circulation half-lives, limited stability, rapid renal clearance, or vulnerability to proteolytic degradation. To improve these properties, polymers such as polyethylene glycol (PEG) have traditionally been attached to proteins through a process known as PEGylation. PEGylation can increase hydrodynamic size, reduce renal filtration, improve solubility, and extend systemic exposure. However, PEG is no longer viewed as the only option for protein modification. Concerns around anti-PEG antibodies, accelerated blood clearance, altered bioactivity, and long-term polymer accumulation have encouraged research into alternative hydrophilic polymers. In this context, polysarcosine has attracted attention as a promising PEG substitute for therapeutic protein conjugation. Ac-pSar16-OH represents a defined pSar oligomer that may be used in studies exploring polymer-protein conjugation, linker design, pharmacokinetic optimization, and next-generation bioconjugate development. Structural Features of Ac-pSar16-OH Ac-pSar16-OH contains a polysarcosine chain with an acetylated terminus and a terminal hydroxyl group. The “pSar16” designation indicates a polysarcosine segment containing sixteen sarcosine units. Sarcosine is an N-methylated glycine derivative, and its incorporation into a polypeptoid backbone gives polysarcosine several properties that distinguish it from conventional peptides. Unlike natural peptides, polypeptoids have side chains attached to the backbone nitrogen rather than the alpha carbon. This structural feature can reduce recognition by proteases and influence conformational behavior. Polysarcosine is also highly hydrophilic and electrically neutral, which makes it useful as a stealth-like polymer in biological environments. The acetyl group in Ac-pSar16-OH can cap one terminus and reduce unwanted reactivity, while the hydroxyl group may provide a site for further functionalization depending on the synthetic strategy. In protein conjugation research, defined oligomers such as Ac-pSar16-OH can be useful for building more controlled conjugates than highly polydisperse polymer mixtures. Why Researchers Are Looking Beyond PEG PEG has played a major role in therapeutic protein modification for decades. PEGylated proteins and peptides have been used to improve half-life, reduce clearance, and enhance formulation properties. However, increased clinical and preclinical experience has also revealed limitations. One concern is immunogenicity. Anti-PEG antibodies have been detected in some individuals, and these antibodies may affect the circulation time, safety, or efficacy of PEG-containing therapeutics. Another issue is accelerated blood clearance, in which repeated administration of PEGylated materials can lead to faster removal from circulation. In addition, PEG is not readily biodegradable, raising questions about long-term tissue accumulation in some applications. These limitations have driven the search for alternative hydrophilic polymers, including polysarcosine, polyoxazolines, polyzwitterions, and other biocompatible materials. Among these, polysarcosine is attractive because it combines water solubility, neutral charge, protein-repellent behavior, and structural similarity to peptide-based materials. Polysarcosine as a PEG Alternative Polysarcosine has been studied as an alternative to PEG for therapeutic protein conjugation. In a frequently cited study, researchers investigated polysarcosine modification of interferon and compared PSar-IFN with a similarly prepared PEG-IFN conjugate. The PSar-IFN conjugate showed comparable ability to protect interferon from protease digestion in vitro and to prolong circulation half-life in vivo. Importantly, the PSar-IFN conjugate retained greater in vitro activity, showed stronger tumor accumulation after systemic administration, and elicited lower anti-interferon antibody responses in mice than PEG-IFN. This research supports the broader idea that polysarcosine can function as a hydrophilic polymer modifier for therapeutic proteins. It may provide some of the pharmacokinetic advantages associated with PEG while potentially reducing certain drawbacks linked to PEGylation. For product-page language, it is accurate to describe Ac-pSar16-OH as a polysarcosine reagent that can replace PEG in therapeutic protein conjugation research. It is better, however, to avoid claiming universal superiority over PEG, because performance depends on polymer length, conjugation site, protein target, dosage, formulation, and disease model. Role in Therapeutic Protein Conjugation Therapeutic proteins often require chemical modification to improve their drug-like properties. Without modification, many proteins are cleared rapidly from the body, degraded by proteases, or limited by poor stability. Polymer conjugation can address these challenges by increasing the apparent molecular size and shielding the protein surface. Ac-pSar16-OH may be used in research workflows where a defined polysarcosine chain is attached to a protein, peptide, or linker intermediate. The pSar segment can increase hydrophilicity and potentially improve the conjugate’s pharmacokinetic profile. Depending on the chemistry used, the terminal hydroxyl group may be activated or converted into another reactive handle for conjugation. In protein conjugation design, polymer placement is important. Site-specific conjugation is often preferred because random modification can reduce biological activity or create heterogeneous mixtures. If the pSar chain is attached near an active site or receptor-binding region, it may interfere with function. If attached at an optimized position, it may preserve activity while improving stability and circulation behavior. Advantages of Polysarcosine-Based Conjugates Polysarcosine offers several research advantages as a protein-conjugation polymer. First, it is hydrophilic. This can improve aqueous solubility and reduce aggregation risk, particularly for proteins, peptides, or drug conjugates that contain hydrophobic regions. Second, it is nonionic. Neutral hydrophilic polymers are often useful in bioconjugation because they can reduce nonspecific interactions with serum proteins, cell membranes, and immune components. Third, polysarcosine has stealth-like properties. Like PEG, it can create a hydrated shell around a protein or nanoparticle surface, potentially reducing recognition and clearance. Fourth, pSar may offer reduced immunogenicity concerns compared with PEG in some experimental systems. In the PSar-IFN comparison study, PSar-IFN elicited considerably less anti-IFN antibody response in mice than PEG-IFN, suggesting that pSar conjugation may help reduce immunological complications in selected settings. Fifth, polysarcosine is structurally related to peptide chemistry. Because it is a polypeptoid, it can be synthesized with defined length and functional end groups, making it attractive for controlled bioconjugate design. Research Applications Ac-pSar16-OH may be useful in multiple research areas related to protein modification and drug delivery. In therapeutic protein conjugation, it can be studied as a PEG alternative for improving half-life, solubility, and proteolytic stability. In peptide-drug conjugate research, pSar segments may be introduced to improve hydrophilicity and reduce aggregation caused by hydrophobic payloads. In ADC and linker research, polysarcosine may be evaluated as a hydrophilic spacer or PEG alternative in linker-payload design, especially when researchers want to reduce hydrophobicity while avoiding PEG-like structures. In nanomedicine, pSar-containing materials may be investigated for stealth coating, circulation extension, or reduced nonspecific protein adsorption. In comparative polymer studies, Ac-pSar16-OH can be used to compare pSar with PEG, polyoxazolines, zwitterionic polymers, and other hydrophilic modifiers. Importance in Cancer and Biopharmaceutical Research Therapeutic protein conjugation has broad relevance in oncology, immunology, endocrinology, infectious disease, and metabolic disease research. In cancer research, polymer-protein conjugates may improve exposure, tumor accumulation, and dosing convenience. The PSar-IFN study is especially relevant because PSar-modified interferon showed stronger antitumor performance than the PEG-modified comparator in the tested mouse model. For biopharmaceutical research, the main value of Ac-pSar16-OH is its potential to help develop next-generation protein conjugates with improved physicochemical and biological profiles. As more therapeutic proteins enter development, researchers need polymer systems that are controllable, reproducible, biocompatible, and compatible with site-specific chemistry. Defined pSar oligomers may help meet this need. Research Considerations Researchers using Ac-pSar16-OH should evaluate several factors during conjugate design. First, polymer length matters. Ac-pSar16-OH is a relatively short pSar oligomer. Longer pSar chains may have stronger effects on hydrodynamic size and circulation half-life, while shorter chains may produce less steric shielding. The optimal chain length depends on the therapeutic protein and the desired pharmacokinetic profile. Second, conjugation chemistry is critical. The hydroxyl terminus may require activation or derivatization before efficient protein coupling. Researchers should choose chemistry that is compatible with the target protein and does not damage sensitive residues. Third, site of conjugation should be optimized. Random conjugation may generate heterogeneous products and reduce activity. Site-specific strategies may improve reproducibility and preserve biological function. Fourth, pSar should be compared directly with PEG or other alternatives in the same experimental system. Claims of improved performance require head-to-head data under comparable conditions. Finally, analytical characterization is essential. Researchers may use HPLC, LC-MS, SDS-PAGE, size-exclusion chromatography, MALDI-TOF MS, dynamic light scattering, activity assays, serum stability assays, and pharmacokinetic studies to evaluate pSar-protein conjugates. Future Research Directions The development of Ac-pSar16-OH and related polysarcosine reagents reflects a broader movement toward beyond-PEGylation technologies. Future studies may focus on optimizing pSar chain length, terminal functionality, conjugation site, and combination with cleavable or non-cleavable linkers. Polysarcosine may also be explored in emerging therapeutic formats, including cytokine conjugates, enzyme replacement therapies, peptide drugs, antibody fragments, nanocarriers, and RNA delivery systems. As researchers continue to evaluate anti-PEG immunity and the limitations of conventional PEGylation, pSar-based materials may become increasingly important in bioconjugation and drug delivery design. Conclusion Ac-pSar16-OH is a defined polysarcosine oligomer that can replace PEG in therapeutic protein conjugation research. Its hydrophilic, nonionic, polypeptoid structure makes it attractive for improving protein solubility, stability, and circulation behavior. Compared with traditional PEGylation, polysarcosine modification may offer advantages in selected systems, including preserved protein activity and reduced antibody responses. As interest grows in next-generation polymer-protein conjugates, Ac-pSar16-OH provides a useful research reagent for studying PEG alternatives, pSar-based bioconjugation, and therapeutic protein optimization. Its role is best understood as a functional polymer building block for designing more refined, hydrophilic, and potentially less immunogenic protein conjugates.
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