Staining with Organic Dyes

Because the ability to dye one protein may differ from that of another in an electropherogram, an unknown protein mix should become stained by different methods. Some of the procedures can be done sequential in the same gel, e.g., additional Coomassie staining after silver staining. 

A synopsis of dyes used for visualization after electrophoresis is given in Table 2.14. 

Staining can also be used for quantifying proteins in gels. The gel is scanned and the obtained picture is calculated by densito-metric software. The amount of protein is proportional to the peak area of the whole band. Since the reaction of a protein with a dye can vary in abroad range (row Bradford in Table 1.1 corresponds to Coomassie staining), caUbration of the intensity is only possible when the same or a very similar protein is used. 

Qualitative interpretation of stained gels is often misleading, since a blank area has not to be protein-free and an intensive band has not to reflect a large amount. 

Dye Staining of Proteins Nucleic acids Color index 

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Rather early in the evolution of bacteriology it was noted that these single-celled organisms readily stain with organic dye molecules. An elaborate classification scheme can in fact be de-... 

The direct microscopic count determines the number of viable and dead microorganisms ia a milk sample. A small amount (0.01 mL) of milk is spread over a 1.0 cm area on a microscope sHde and allowed to dry. After staining with an appropriate dye, usually methylene blue, the sHde is examined with the aid of a microscope (oil immersion lens). The number of bacterial cells and clumps of cells per microscopic field is determined and, by appropriate calculations, is expressed as the number of organisms per milliliter of sample. 

Now, to return to the orange stain, formed on the surface of a pan by adsorption of capsaicin from a solution (the curry). Such organic dyes are usually unsaturated (see the structure I above), and often comprise an aromatic moiety. The capsaicin, therefore, has a high electron density on its surface. During the formation of the adsorption bond, it is common for this electron cloud to interact with atoms of metal on the surface of the pan. Electron density flows from the dye molecule via the surface atoms to the conduction band of the bulk metal. The arrows on Figure 10.4 represent the direction of flow as electron density moves from the charge centroid of the dye, through the surface atoms on the substrate, and thence into the bulk of the conductive substrate. 

Gels are stained very sensitive and quick by combination of Coomassie Brilliant Blue R250 with Bismarck Brown R (Basic Brown4 C.1.21010). In our opinion, this is the best staining method using organic dyes. 

Schumann R. and Rentsch D. (1998) Staining particulate organic matter with DTAF—a fluorescence dye for carbohydrates and protein a new approach and application of a 2D image analysis system. Mar. Ecol. Prog. Ser. 163, 77-88. 

Bacterial peliosis hepatis has been determined in cases of HIV infection and cat-scratch fever, where it is caused by Rochahmaea quintana bacteria (Bartonella henselae), (s. p. 482) It presents as a proliferation of blood-filled cystic sinusoidal cavities, which are surrounded by fibromyxoid stroma (M.J. Dolan et at, 1993). Sometimes it is possible to identify the causative organism using PCR or staining with a silver dye (War-thin-Starry). Treatment can then follow with antibiotic agents, such as erythromycin, doxycyclin or clarithromycin. 

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