NHS-PEG4-(m-PEG4)3-ester

Name: NHS-PEG4-(m-PEG4)3-ester
Brand: BOC Sciences
Rating: 5 (1 reviews)

CAS No.: 1333154-70-3

Cat No.: BP-501585 4.5

NHS-PEG4-(m-PEG4)3-ester is a heterobifunctional polyethylene glycol (PEG) linker built around an N-hydroxysuccinimide (NHS) ester at one terminus and a branched, multi-PEG segment at the other. The structure combines a short PEG4 spacer with a branched motif comprising three additional PEG4 arms, providing a flexible, hydrophilic scaffold that increases effective linker length and reduces nonspecific interactions. In PROTAC and targeted protein degradation workflows, the NHS ester serves as a reactive handle for forming stable amide bonds with primary amines on ligands such as lysine-containing peptides, antibody fragments, or small-molecule handles bearing amine groups. The PEG-rich region then acts as a solubilizing and spacing element, helping to position the two recruited components to favor productive ternary complex formation while mitigating steric hindrance. This linker is valuable for constructing modular conjugates where controlled attachment chemistry and improved aqueous compatibility are critical for maintaining degradation activity.

Structure of 1333154-70-3

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PROTAC Linker

Molecular Formula

C₆₀H₁₁₀N₆O₂₈

Molecular Weight

1363.54

* For research and manufacturing use only. Not for human or clinical use.

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IUPACName

(2,5-dioxopyrrolidin-1-yl) 5-[2-[2-[2-[2-[3-[[1,3-bis[3-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethylamino]-3-oxopropoxy]-2-[[3-[2-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]ethylamino]-3-oxopropoxy]methyl]propan-2-yl]amino]-3-oxopropoxy]ethoxy]ethoxy]ethoxy]ethylamino]-5-oxopentanoate

InChI Key

CPFQBAXMDMJPOZ-UHFFFAOYSA-N

InChI

InChI=1S/C60H110N6O28/c1-75-25-28-83-41-44-87-37-33-80-22-14-62-53(68)9-18-91-49-60(50-92-19-10-54(69)63-15-23-81-34-38-88-45-42-84-29-26-76-2,51-93-20-11-55(70)64-16-24-82-35-39-89-46-43-85-30-27-77-3)65-56(71)12-17-78-31-36-86-47-48-90-40-32-79-21-13-61-52(67)5-4-6-59(74)94-66-57(72)7-8-58(66)73/h4-51H2,1-3H3,(H,61,67)(H,62,68)(H,63,69)(H,64,70)(H,65,71)

SMILES

COCCOCCOCCOCCNC(=O)CCOCC(COCCC(=O)NCCOCCOCCOCCOC)(COCCC(=O)NCCOCCOCCOCCOC)NC(=O)CCOCCOCCOCCOCCNC(=O)CCCC(=O)ON1C(=O)CCC1=O

1. 4-isoxazolyl-1,4-dihydropyridines: a tale of two scaffolds

Nicholas R Natale, Scott A Steiger Future Med Chem. 2014 May;6(8):923-43.doi: 10.4155/fmc.14.46.

The association of the isoxazole and dihydropyridine (DHP) ring systems fused at the 4'-isoxazolyl- to the 4-position of the DHP has produced a combination scaffold, the isoxazolyl-DHPs (IDHPs) with unique conformational characteristics. The IDHPs are useful in probing biological activity, as exemplified by our efforts in the fields of voltage gated calcium channel (VGCC) antagonists and inhibitors of the multi-drug resistance (MDR) transporter. A strategically placed methyl group produced a signifcant change at the VGCC, with (R)-(+)-1-phenyl-prop-2-yl (3.7 nM) > phenethyl (22.9 nM) > (S)-(-)-1-phenyl-prop-2-yl (210 nM), a eudismic ratio of 56.7. Branching at the C-5 of the isoxazole produced a 25% increase in MDR binding, and replacing the DHP C-3 ester with a functionalized amide also gave a dramatic increase in binding affinity. Opportunities for combined scaffolds - including examples containing IDHPs - are waiting to be discovered: because new biology is driven by new chemistry.

2. Milk lipoprotein lipases: a review

P G Jensen, R E Pitas J Dairy Sci. 1976 Jul;59(7):1203-14.doi: 10.3168/jds.s0022-0302(76)84348-2.

Lipoprotein lipase activity has been found in the milks from severals species where it is assumed to result from leakage from the mammary gland into milk. The function of the enzyme in the gland is apparently to assist in the transfer of blood lipoprotein triacylglycerol fatty acids into milk triacylglycerols. Bovine skim milk is one of the richest sources of lipoprotein lipase and this enzyme has been purified extensively (7000 fold) by affinity chromatography. The lipase has a molecular weight of about 62000, is inhibited by protamine sulfate, 1.0 M sodium chloride, apolipoprotein C-I (apolipoprotein-serine), and apolipoprotein C-III (apolipoprotein-alanine). The enzyme is activated by apolipoprotein C-II (apolipoprotein-glutamic acid), serum, and by heparin to which it also binds. The lipase is highly specific for the primary esters of acylglycerols and exhibits a slight stereospecificity for the sn-1 ester in preference to the sn-3-ester. Bovine milk also has separate activity toward 1-monoacylglycerols. Human milk contains a serum stimulated lipoprotein lipase with many of the characteristics of the enzyme in bovine milk, as well as an enzyme stimulated by bile salts which resembles the sterol ester hydrolase of rat pancreatic juice. The assay, function, purification, characteristics, and substrate specificities of these enzyme are discussed.

3. Chemotherapeutic potential of phosphodiesterase inhibitors

M J Perry, G A Higgs Curr Opin Chem Biol. 1998 Aug;2(4):472-81.doi: 10.1016/s1367-5931(98)80123-3.

The application of molecular cloning has revealed the phenomenal diversity and complexity of the phosphodiesterase isoenzyme family. Thus, more than 30 human phosphodiesterases are now known; all are apparently necessary for the seemingly simple task of hydrolysing the 3'-ester bond of either cyclic adenosine monophosphate or cyclic guanosine monophosphate. The availability of phosphodiesterase isoenzymes as pure recombinant proteins has greatly facilitated the identification of potent, selective inhibitors. The potential of these inhibitors to therapeutically exploit the molecular diversity of the phosphodiesterases has progressed significantly. A number of drugs are in clinical trials for asthma, and Viagra has become the first selective phosphodiesterase inhibitor to be approved by the US Food and Drug Administration.

This PROTAC linker, NHS-PEG4-(m-PEG4)3-ester, is designed to provide a flexible polyethylene glycol-based spacer that improves solubility and enables efficient conjugation to targeting ligands. The NHS-activated ester functionality supports robust amide-bond formation under mild aqueous conditions, while the PEG architecture helps tune linker length, reduce steric constraints, and support effective ternary complex formation in targeted protein degradation workflows. Detailed structural and reactivity considerations are provided below.

Structure: The linker comprises an N-hydroxysuccinimide (NHS) activated ester connected to a PEG4 segment and three additional m-PEG4 units, yielding a highly flexible, hydrophilic polyether chain. It contains an activated carbonate/ester linkage for acyl transfer and ether linkages that confer conformational mobility and water compatibility.

Reactivity: The NHS ester reacts with primary amines to form stable amide bonds, typically via nucleophilic acyl substitution. Suitable conditions involve mildly basic aqueous buffers or mixed aqueous/organic systems that maintain amine nucleophilicity while minimizing hydrolysis of the activated ester. Common catalysts are not required; careful control of pH, temperature, and reaction time helps preserve reactivity. After coupling, the product is generally purified to remove NHS byproducts and unreacted starting materials.

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* Our calculator is based on the following equation:
Concentration (start) x Volume (start) = Concentration (final) x Volume (final)
It is commonly abbreviated as: C₁V₁ = C₂V₂