(+-)-Blebbistatin

(+-)-Blebbistatin is a racemic mixture of (-)-blebbistatin (Item No. 13013) and (+)-blebbistatin (Item No. 13165), the active and inactive forms, respectively. (-)-Blebbistatin is a selective cell-permeable inhibitor of non-muscle myosin II ATPases.{16452,17037} (-)-Blebbistatin rapidly and reversibly inhibits Mg-ATPase activity and in vitro motility of non-muscle myosin IIA and IIB for several species (IC50s = 0.5-5 µM), while poorly inhibiting smooth muscle myosin (IC50 = 8 µM).{17036} Through these effects, (-)-blebbistatin blocks apoptosis-related bleb formation, directed cell migration, and cytokinesis in vertebrate cells. However, prolonged exposure to blue light (450-490 nm) results in degradation of blebbistatin to an inactive product via cytotoxic intermediates, which may be problematic for its use in fluorescent live cell imaging applications.{17038,24037} (S)-nitro-Blebbistatin (Item No. 13891) and (R)-nitro-blebbistatin (Item No. 9001935) are more stable forms of (-)-blebbistatin and (+)-blebbistatin, respectively. The addition of a nitro group stabilizes the molecules to circumvent their degradation by prolonged blue light exposure.{16725} (S)-nitro-Blebbistatin and (R)-nitro-blebbistatin have the same stereochemistry of the active and inactive enantiomers, respectively.