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Label monoclonal antibodies site specifically with ETAC reagents

ETAC and labeling monoclonal antibodies

Monoclonal antibodies and their small fragments (Fabs, scFv, diabodies etc.) are intriguing objects for creation of protein-based medicines. These proteins can be site-specifically modified with ETAC-dPEG® (“ETAC” abbreviates “Equilibrium Transfer Alkylation Cross-link”; “dPEG®” is the registered trade name for “discrete Poly(Ethylene Glycol)”) reagents. Using ETAC, a three-carbon bridge is formed linking the two cysteine sulfur atoms. The dPEG® attached to the ETAC reduces the protein’s immunogenicity and prevents rapid clearance of the protein from the bloodstream. This, in turn, helps to maintain a desired therapeutic concentration between doses, thereby reducing the risk of loss of efficacy. The structure of ETAC-reagent and generation of the dPEG®-monosulfone which undergoes a site-specific conjugation with a Fab are outlined below in Figure 1. For details, see, for example, “Comparative binding of disulfide-bridged PEG-Fabs”, Bioconjugate Chemistry (2012), 23, 2262-2277; and “Disulfide bridge based PEGylation of proteins”, Advances in Drug Delivery Reviews (2008), 60, 3-12.
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Superior Surface Protection of Gold Nanoparticles With Short-Chain PEG

Surface protection of gold nanoparticles is improved by using short-chain, alcohol-terminated dPEG® linkers rather than (2-mercaptopropanoyl)glycine (tiopronin) or mercapto-undecyl-tetraethyleneglycol, according to research findings from the lab of David E. Cliffel, Department of Chemistry, Vanderbilt University. Short-chain dPEG®s increase water solubility, are non-toxic, and show no immune response to anti-PEG antibodies at low concentrations.(1) Continue reading

Thiol reactive crosslinker PN10214, one of Quanta BioDesign's most popular PEGylation reagents, has a thiol reactive maleimide group on one end and an amine reactive NHS ester on the other end of a tetraethylene glycol linker.

Thiol Reactive Crosslinkers for Bioconjugation

Thiol reactive crosslinkers are one of the most common classes of crosslinkers in bioconjugation (1). Because most proteins contain far more free amines than thiols and disulfides, conjugation to a thiol allows for greater control of the conjugation. Even more control of the conjugation process is afforded if a thiol reactive compound is combined with an amine reactive compound to create a heterobifunctional crosslinker. Continue reading

Organophosphorus Hydrolase Pharmacokinetics and Immunogenicity are Improved by Branched dPEG®

Organophosphorus hydrolase  (OPH, EC 8.1.3.1), also known as Aryldialkylphosphatase, is a remarkably stable homodimeric enzyme that can detoxify organophosphate compounds. Organophosphate compounds are the basis of numerous pesticides (e.g., malathion) and chemical warfare weapons (e.g., sarin, VX). Organophosphates act by blocking the action of the enzyme acetylcholinesterase. Overuse and misuse of organophosphate pesticides are major causes of acute pesticide poisoning and death. See also here. Continue reading

A dPEG®ylated Avibody provides an example of the discrete nature of Quanta BioDesign's dPEG® reagents..

Noise control and removal through dPEG®ylation

Noise control and removal is important in any discipline where clean, clear signals are critical in measurement and data collection. For this reason, whilst the saying ‘Beauty is in the eyes of the beholder’ may be true in many instances, scientific research cannot permit subjective, qualitative thinking to trump objective data. Continue reading