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We are exhibiting at the BIO International Convention at the Boston, MA Convention & Exhibition Center from June 18-21, 2012. Come visit us at Booth 782. We look forward to meeting you there!
We have a special promotion this month for new custom peptide synthesis orders. Mention the word Backpack in the comments field of our online ordering form and we will send you one of our brand new 25th Anniversary drawstring backpacks along with your peptide(s).
BIO (Boston, MA)
6/18-21, 2012 (booth #782)
32nd European Peptide Symposium (Athens, Greece)
9/2-7, 2012 (stand #14)
CPhI (Madrid, Spain)
10/9-11, 2012 (stand 4F46NA)
In the News
Speciality Chemicals Magazine
May 1, 2012
Peptide Word Puzzle
Find the hidden peptide word in the 96 well plate below. The word may be written forward, backward, horizontally, vertically, or diagonally. The first five people to find the hidden peptide word win a $10 Amazon gift card! Email your answers to: firstname.lastname@example.org.
Peptide Wire - Edition 8 (June 2012)
Click Reactions in Peptide Chemistry
What is a Click Reaction?
Click reactions are popular techniques for generating substances quickly and reliably by joining small units together. The term "click chemistry" implies that: the reactions are highly efficient, wide in scope, product isolation is easy, stereospecific, simple to perform using inexpensive reagents, and can be conducted in benign solvents such as water. The Copper-Catalyzed variant of Huisgen Azide-Alkyne Cycloaddition (CuAAC) fits the concept well and is one of the most popular prototype click reactions to date. Click chemistry is finding a number of applications in the areas of drug discovery, bio-conjugation, radiolabelling, material science, nanotechnology, supra-molecular chemistry, and polymer science.
Applications in Peptide Science
Click chemistry provides a number of avenues for peptide/protein modifications and could be combined with other techniques to make complex structures and multi-component functionalized systems with ease. The chemistry could be performed in different ways. For example, peptides can be converted post-synthetically to an azido derivative which can be clicked with appropriate substrate containing a clickable alkynyl group or vice versa. Peptides can also be made by inter- and intramolecular click reactions using azide or alkyne containing amino acids or building blocks during peptide synthesis. Building blocks containing clickable moieties will be instrumental for constructing side-chain modified peptides, interside-chain peptide chimera, peptide small molecule conjugates, and cyclic peptides. Solid phase resins modified with clickable groups can also be used for making clickable/modified peptides. Click chemistry is compatible with various protected amino acid side chains used in peptide synthesis. The triazole linkage formed through click reaction resembles an amide bond due to its relative planarity and strong dipole moments.
The power of click chemistry has already been demonstrated in peptide applications such as chemical ligation, cyclization, bio-conjugation, imaging, and peptidomimetics design - conformational and back bone modifications. A number of reagents and building blocks can be used for peptide click chemistry. These include azido-amino acids, non-fluorescent azides, PEG and spacer azide and alkynes, azides and alkynes of fluorescent dyes, quencher dyes, nucleosides and nucleotides, alkyne and azide containing chemical modification reagents, diazo transfer reagents and propargyl amino acids.
Cu-free Click Reactions
The cytotoxicity of copper remains a concern and a limiting factor for widespread in vivo application of the CuAAC click reaction. The presence of copper and/or reducing agents can cause degradation or aggregation of the targeted biomolecules. Fortunately, these challenges can be overcome by the use of copper-free click chemistry. This technique is based on the reaction of cyclooctynes (such as OCT, MOFO, DIBO, DIFO) with azides in the absence of Cu catalyst at low temperature giving better efficiency than the CuAAC reaction. The copper-free click reaction is very useful for in vivo chemoselective ligation applied to biomolecules like Staudinger ligation (phosphine-azide reaction), and is several times faster than the latter.
A recent application of Cu-free click chemistry to peptides include the synthesis of a DOTA-peptide conjugate prepared by the attachment of DOTA to monofluoro-cyclooctyne (MOFO) followed by bioconjugation to an azide-modified α-MSH peptide. The resulting conjugate can be radiolabelled for imaging applications such as tumor targeting. DOTA is used as part of some cancer therapies, where it functions as a chelating agent for radioisotopes. Conjugation of DOTA to peptides is not compatible with the CuAAC reaction due to the possible chelation of copper to DOTA.
In the future, the applications of click chemistry to peptides will grow significantly due to the potential of these molecules in drug development, diagnostics, cosmetics and material science combined with the simplicity and efficiency of click reactions.
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