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Three Click Chemistry Ideas for PEGylation Reagents

Have you ever been working your way through a product catalog and encountered a product you weren’t sure how to use? I know I have. It helps in those moments of “What do I do with this?” to have some tips on how to use a product effectively. Today I want to take one of our unique click chemistry discrete PEGylation (dPEG®) reagents, PN10524, azido-dPEG®11-amine, and offer three ideas on how to get the most out of it in an application. Continue reading

Title Slide of Paul Davis' talk at the 7th Annual World ADC Summit in San Diego, given October 11, 2016. The talk is titled "Using the dPEG as the Framework to Uniquely Load and Protect Payloads in an ADC Format with dPEG Single Molecule Precision"

Our World ADC 2016 Presentation

The World ADC Summit in San Diego was held October 10-13, 2016. This was the 7th Annual World ADC Summit. On October 11, 2016, our company president, Paul D. Davis, presented his talk titled, “Using the dPEG® as the Framework to Uniquely Load and Protect Payloads in an ADC Format …with dPEG® single molecule precision.” Continue reading

Graph showing the relationship of dPEG® linker length in relation to potency and specificity in extracellular drug conjugates.

Extracellular Drug Conjugates Therapeutically Exploit Protein Proximity

Pharmaceutical company Centrose, founded by James R. Prudent, Ph.D., developed a new class of antibody drug conjugates called extracellular drug conjugates. Nature Publishing Group published the research as a open access paper in its Molecular Therapy journal.1 Apart from the interesting and important development of a new class of antibody drug conjugate (ADC), the research also showed how important linker length 2 is to the potency and specificity of the EDC. Continue reading

Amphotericin B conjugated to a discrete PEG (dPEG®) linker with a free amine have higher water solubility and lower toxicity than the parent compound.

Amphotericin B+dPEG®: Water-Soluble, Less Toxic, Potent

Amphotericin B conjugated to a discrete PEG (dPEG®) linker with a free amine have higher water solubility and lower toxicity than the parent compound.
Amphotericin B conjugated to a discrete PEG (dPEG®) linker with a free amine has  higher water solubility and lower toxicity than the parent compound. Image used by permission from J. Med. Chem. (2016), 59, 1197-1206, copyright 2016, American Chemical Society.

About Amphotericin B

Structure of Amphotericin B. Used with permission from J. Med. Chem. (2016), 59, 1197-1206, copyright 2016, American Chemical Society.
Figure 1: Structure of Amphotericin B. Image used by permission from J. Med. Chem. (2016), 59, 1197-1206, copyright 2016, American Chemical Society.

Amphotericin B (Figure 1) is the “gold standard” treatment for systemic fungal infections and diseases caused by the parasite Leishmania. Sometimes it is the only effective treatment because drug resistance renders other treatments useless. Systemic fungal infections are an increasingly serious, widespread problem in medicine. Patients with weakened or suppressed immune systems (caused by HIV/AIDS, diabetes, organ transplants, some cancer treatments) are especially at risk. An estimated 1.5-2 million people die each year from systemic fungal infections (1). Despite its “gold standard” label, there are several difficulties with Amphotericin B. Continue reading

Chemical structure of PN10283, Fmoc-N-amido-dPEG®12-acid

SNARE-Mediated Membrane Fusion and dPEG®, Part 1

Part 1: A Reduced SNARE Model for Membrane Fusion

The cells of all living things depend on membrane fusion for intra- and intercellular transport of molecules. In both cellular membrane fusion and intracellular vesicle fusion, the fusion process is controlled and guided by SNARE proteins. SNARE is an acronym for Soluble NSF Attachment Protein Receptor. NSF stands for N-ethylmaleimide-Sensitive Factor. Reviews of SNARE protein structure and function can be found here, here, here, and here. An example of a SNARE protein is synaptobrevin. Click part 2 and part 3 to read the other pieces in this series. Continue reading

Schematic drawing of a TOPO coated green quantum dot, approximately 3 nm in diameter.

dPEG® Eliminates Non-Specific Binding on Quantum Dots

What about Quantum Dots?

Let’s start with a quick refresher. Quantum dots are cool little tiny nano particles, less than 10 nm in diameter, made of a semiconductor alloy core and coated with a shell of a different alloy, which fluoresce at different wavelengths depending on their size and specific composition. The smaller the quantum dot, the more blue-shifted its emission wavelength while larger quantum dots (6 nm and larger) shift to red and near-IR. Quantum dots can be a good alternative to organic dyes since they have broad excitation spectra (absorb energy at a wide range of wavelengths), narrow emission spectra (emit a fairly specific wavelength), and don’t suffer from photobleaching (degradation due to light intensity/oxidizing agents). Read more about fluorescence excitation and emission. Continue reading

Chart showing the analgesic activities of various galanin analogues used in a formalin pain assay.

PEGylated Galanin Shows Enhanced Analgesic Effects in PNS

Galanin is a naturally occurring neuropeptide in the human body that facilitates communication between cells to balance a myriad of physiological functions. Neuropeptides are biosynthesized molecules used by the human body for everything from neurogenesis to cell communication.  Galanin’s main receptor sites reside in the central nervous system (CNS), and it normally crosses the blood brain barrier; however, the peripheral nervous system (PNS) also reacts directly to galanin and its receptors in sites of pain mediation.1  Continue reading

dPEG®-Modified Diabodies Improve Tumor Imaging

Researchers in Australia and the United States have shown that dPEG®-modified diabodies improve positron emission tomography (PET) imaging of tumors by reducing kidney uptake of diabody and extending diabody half-life in the bloodstream, which thus allows more diabody to be taken up by the tumor.1 These findings suggest that better tumor imaging can be achieved using less material, because more of the diabody that targets the tumor gets to the tumor and less of it is excreted by the kidney. Continue reading