Coomassie Brilliant Blue G-250 is used for protein staining in SDS-PAGE, Blue Native PAGE, and the Bradford Method, with high band visibility. In the staining reaction, the Coomassie dye binds to proteins through ionic interactions between sulfonic acid groups and positive protein amine groups through Van der Waals attractions. The gels are soaked in dye and excess stain is then eluted with a solvent (“de-staining”). This treatment allows the visualization of protein bands.
Brilliant Blue G is also a selective inhibitor of the P2X purinoceptor channel P2X7 [1].
P2X receptors are membrane ion channels activated in response to the binding of extracellular ATP. Seven P2X subtypes have been identified. P2X receptors have been involved in in diverse patho- and physiological processes, such as the autonomic nervous system, afferent signalling, chronic pain, and in autocrine loops of endothelial and epithelial cells. The P2X7 receptor plays a prominent role in certain neurologic disorders, such as ischemia-reperfusion injury, Alzheimer's disease, spinal cord injury and sensory neuropathies [2].
In HEK293 cells heterologously expressing human P2X7 receptors, Brilliant Blue G noncompetitively inhibited rat and human P2X7 receptors with IC50 values of 10 and 200 nM, respectively. The IC50 values for inhibition of the other P2X receptors ranged from 2 to >30 μM; Brilliant Blue G inhibited the rat and human P2X4 receptors with the IC50 values of >10 and 3.2 μM [1]. Subretinal injection of BBG caused retinal cell degeneration at lower concentrations. Subretinal injection of BBG (0.25 mg/mL) provided satisfactory biocompatibility [3].
References:
[1] Jiang L H, Mackenzie A B, North R A, et al. Brilliant blue G selectively blocks ATP-gated rat P2X7 receptors[J]. Molecular pharmacology, 2000, 58(1): 82-88.
[2] Sperlágh B, Vizi E S, Wirkner K, et al. P2X 7 receptors in the nervous system[J]. Progress in neurobiology, 2006, 78(6): 327-346.
[3] Ueno A, Hisatomi T, Enaida H, et al. Biocompatibility of brilliant blue G in a rat model of subretinal injection[J]. Retina, 2007, 27(4): 499-504.