MAL-dPEG?36-NHS ester, product number QBD-10904, is a crosslinking reagent that joins a sulfhydryl to a free amine through a hydrophilic bridge. The sulfhydryl groups react with a maleimide group via a Michael addition reaction. The amines form amide bonds with the crosslinker by nucleophilic substitution of the N-hydroxysuccinimidyl (NHS) ester of a carboxylic acid group. The maleimide and NHS functional groups on the crosslinking compound sit at either end of a long (118 atoms, 134.8 ?), discrete-length polyethylene glycol (dPEG?) chain.nReactions that join free amines with free thiols are among the most popular, most useful crosslinking reactions in bioconjugate chemistry. These reactions require heterobifunctional reagents that bridge the two groups. Traditional crosslinkers are hydrophobic molecules. Vector Laboratories' dPEG? crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths.nThe conjugation of conventional hydrophobic crosslinking reagents to biomolecules almost inevitably triggers problems such as aggregation and precipitation of the conjugates. These problems do not occur with our water-soluble, non-immunogenic dPEG? crosslinkers.nBecause NHS esters hydrolyze readily in water or aqueous buffer, the NHS ester end of the molecule must conjugate to a target molecule before conjugating the maleimide end of the molecule. At pH 7.0 – 7.5, NHS esters react optimally with free amines. However, NHS esters can react with free amines with pH as low as 6.5. As the pH increases, the hydrolysis rate of the NHS ester increases. Indeed, at pH 8 and 25°C, the half-life of an NHS ester in aqueous media is one hour, while at pH 8.6 and 4°C, the half-life falls to ten (10) minutes.[3] Thus, we strongly discourage storing MAL-dPEG?36-NHS ester, product number QBD-10904, in water or aqueous buffer. Instead, we recommend that customers make new solutions of the product as needed, use them immediately, and discard unused solutions after use.nThe reaction of the maleimide end of MAL-dPEG?36-NHS ester with a sulfhydryl proceeds optimally at pH 6.5 – 7.5. Use the lowest reasonable pH within this range. Above pH 7.5, free amines compete with free thiols at the maleimide reaction site, which can cause confusing results. Moreover, at higher pH values, the maleimide ring may open to form unreactive maleamic acid.nThe use of MAL-dPEG?36-NHS ester, product number QBD-10904, has been published in numerous scientific paper and patents. The following list highlights some of the more interesting uses of this product:ndevelopment of extracellular drug conjugates (EDCs), a type of ADC for extracellular markers;ntargeted delivery of cancer drugs;nas a long, flexible tether for atomic force microscopy (AFM); andnas a surface coating for amine-functionalized nanoparticle surfaces.
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Click Chemistry Tools(CCT)公司位于美國亞利桑那州斯科茨代爾(Scottsdale,AZ)。自公司成立以來,一致致力于不斷開發(fā)和擴展一系列連接產(chǎn)品。他們利用特別新的研究成果研發(fā)生產(chǎn)出新穎的交聯(lián)和標記試劑。產(chǎn)品被廣泛用于藥物研發(fā)、癌癥治療以及各類診斷技術(shù)等。此外,CCT還可以提供個性化的定制產(chǎn)品,已滿足不同用戶的需求。目前CCT的產(chǎn)品線主要包括:Azides(Biotin-Azides)試劑、Bis-sulfone交聯(lián)試劑、DBCO試劑、TCO試劑、Terminal Alkyne試劑、Tetrazine試劑、標記試劑盒以及分選用底物等。nFluoroprobes公司位于美國亞利桑那州斯科茨代爾(Scottsdale, AZ),自成立以來,一直致力于不斷開發(fā)一系列的連接(linker)產(chǎn)品。利用特別新的研究成果研發(fā)生產(chǎn)出各類新穎的交聯(lián)和標記試劑。其產(chǎn)品被廣泛用于藥物研發(fā)與篩選、疾病治療方法和診斷技術(shù)等領(lǐng)域。此外,F(xiàn)luoroprobes還可以根據(jù)客戶的個性化需求提供各類定制連接產(chǎn)品。代表產(chǎn)品有Classic Fluorescent Dyes, AZDye, Cyanine Dyes, IR Dyes, MB dyes以及一些標記試劑盒等。nQuanta Biodesign公司位于美國中部的俄亥俄州,成立于1997年。也是專注于生產(chǎn)研發(fā)各類標記產(chǎn)品的品牌之一。其研發(fā)的產(chǎn)品與dPEG技術(shù)相結(jié)合,生產(chǎn)出他們獨有的專利產(chǎn)品dPEG Building Blocks and Linkers,被廣泛用于細胞治療和分子診斷等研究領(lǐng)域。另外,還可為廣大科研工作者提供多種化學修飾試劑以及傳統(tǒng)Liner等。n目前上述三個品牌都已被被Vectorlabs收購并整合到Vectorlabs產(chǎn)品中