New Products for Detection Applications

UV-detectable IEF Markers

Isoelectric focusing (IEF) is a powerful analytical tool for the separation of proteins. In order to ensure the high performance of analysis, isoelectric point (pI) standards are needed. In addition to classical protein based standards, low molecular weight compounds have been developed and succesfully examined in capillary IEF and IEF-gel electrophoresis. Gel electrophoresis, the common technology for IEF, minimizes convection and introduces an additional gel-sieving effect to separate proteins by size. However, it has several disadvantages such as lengthy analysis time, limited resolution, and difficulty in detection. These challenges have been largely overcome by the development of IPG-strips (immobilized pH gradients) for use in high-resolution pI-separation.

Capillary electrophoresis is a high-resolution approach to separate molecules based on the pI point that can be automated. Separation is carried out in fused-silica capillaries with internal diameters of 25 - 75 μm. The electrophoresis takes place in free solution and the capillary controls convection currents. After focusing is complete, the solutes are pumped out of the capillary. UV absorption is the most popular detection method for capillary IEF. These UV-detectable pI markers are recommended for use in HPCE and IEF gels and cover a pI range of 3.7-10.4. The markers have an extraordinarily strong absorbance rate and high stability that enables sensitive detection.

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MegaStokes Dyes for Click Labeling

MegaStokes dyes are characterized by a broad shift between absorption and emission maximum. For most dyes, Stokes shifts are approximately 20 nm – 40 nm. This new series of MegaStokes dyes covers a broad wavelength region and has Stokes shift values up to 120 nm. Dyes with larger Stokes shifts are recommended for multiplex applications and resonance electron transfer (FRET). The MegaStokes dyes are modified with reactive azide or alkyne moieties to support copperfree or copper-catalyzed click reactions. Experimental studies on Chinese hamster ovary (CHO) has shown no toxicity of these dyes up to concentration of 50 μM.3

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Chromeo™ Py-Dyes for Protein Labeling

Chromeo Py-dyes are a new class of amino-reactive fluorescent protein stains that have a spectral shift and dramatic increase of quantum yield upon binding to proteins. Unbound Py-dye is hydrolyzed during labeling, eliminating the need for post-labeling purification. Chromeo Py-dyes are stable in aqueous solutions and use a simple one-step reaction under ambient temperature. Chromeo Py-dyes are licensed from Active Motif, Inc.

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Using MTS (methanethiosulfonate) derivatives is a powerful strategy to covalently label biomolecules. The MTS group rapidly reacts with thiol groups of proteins and requires less material for complete reaction than comparable maleimide, iodoacetate or NHS-ester conjugation reactions.

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  1. Monofunctional carbocyanine dyes for bio- and bioorthogonal conjugation. Shao, F., et al., Bioconjugate Chem., 19, 2487 (2008).
  2. In vivo imaging of membrane-associated glycans in developing zebrafish. Laughlin, S.T., et al., Science, 320, 664 (2008).
  3. Clickable fluorophores for biological labeling-with or without copper. Kele, P., et al., Org. Biomol. Chem., 7, 3486.B (2009).

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