The CyDye family of fluorescent dyes is currently the overwhelming choice for applications in proteomic analysis, using two-dimensional difference gel electrophoresis (2D-DIGE). Protein labeling with CyDyes is hampered by protein precipitation and gel smearing when used above minimal labeling. The solubility of labeled protein may be improved by introducing water solubilizing groups on the dye such as cysteic acids. However, addition of a negatively charged functionality will have the undesired effect of shifting the pI in relation to the unlabeled protein. These limitations have been addressed through the synthesis of highly water-soluble and pI balancing zwitterionic CyDye fluorophores (Z-CyDyes). The new dyes feature a cysteic acid motif, a titratable amine functionality and a NHS activated ester group. In side by side 2D-DIGE comparisons of Z-CyDyes and CyDyes, the new dyes significantly enhanced protein spot volume and the number of spots that were detected. Z-CyDyes have the potential to enhance the depth of proteome coverage and provide a general strategy for improving the performance of protein tagging reagents.
We present an adaptation to an experiment previously published in this Journal. The experiment was designed to determine the heat capacity ratios of gases by measuring the speed of sound using a modified Kundt’s tube. The experiment yielded excellent results for all of the gases and gas mixtures measured. Although elegant in its simplicity, it made use of an expensive pulsed laser that is not a common piece of equipment at most liberal arts institutions. By replacing the laser with an inexpensive function generator and speaker, we found that our results were of comparable accuracy and precision.
The syntheses of eleven sultam thioureas, including nine new compounds, are described. These compounds were synthesized from thioureas and include the first sultam thioureas in which the two thiourea nitrogen groups are not identical. In addition, the first X-ray crystal structures of sultam thioureas and the antiviral activity of these compounds against West Nile virus (WNV) are reported.
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