Stains for Protein Visualization

Proteins vary in their interactions with stains. A protein spot that can be visualized using one staining protocol may not be visible when a different stain is applied. Therefore, it is important to evaluate the efficacy of multiple stains with each new sample and select the stains that generate the best results.

The most popular gel stains are Coomassie Brilliant Blue R-250 and Bio-Safe Coomassie Brilliant Blue G-250. These stains are less sensitive than other protein stains, but they interact uniformly with all proteins. Silver stains are more sensitive; however, they have a limited dynamic range and do not bind to all proteins uniformly.

The more sensitive Flamingo fluorescent gel stain is ideal for nonspecific visualization and quantitation of proteins in SDS-PAGE gels. It uses an easy two-step protocol that can be completed in as little as 5 hours and does not require destaining. Moreover, the steps are not time-sensitive, and the dye will not overstain the gels.

Protein Stain	Lower Limit of Sensitivity	Linear Range	Cost	Imaging System Requirements	Mass Spectrometry Compatibility
Bio-Safe Commassie G-250 stain	5–10 ng	2 orders of magnitude	++	Densitometer	+++++
Coomassie Blue R-250 stain	10–25 ng	2 orders of magnitude	+	Densitometer	+++++
Silver stain kit (Merril method)	0.5–1 ng	1 order of magnitude	+++	Densitometer	Not compatible
Silver Stain Plus kit	0.5–1 ng	1 order of magnitude	+++	Densitometer	++
Dodeca silver stain	0.5–1 ng	1 order of magnitude	+++	Densitometer	+++
SYPRO Ruby protein gel stain	1–10 ng	3 orders of magnitude	+++++	Fluorescent	++++
Flamingo fluorescent gel stain	0.25–0.5 ng	>3 orders of magnitude	++++	Fluorescent	+++++

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