(-)-Blebbistatin

(-)-Blebbistatin is one of the configurations of the racemic mixture (±)-Blebbistatin (Cat. No. GC12341) and is the active form. (-)-Blebbistatin is a cell-permeable inhibitor of non-muscle myosin II ATPase, which effectively inhibits multiple striated muscle myosins as well as vertebrate non-muscle myosins with IC₅₀ values ranging from 0.5-5μM, and only slightly inhibits smooth muscle myosin (IC₅₀=80μM) ^{[1, 2]}. (+)-Blebbistatinb has no effect on the ATPase activity of various myosin IIs or cell migration in cultured smooth muscle^[3]. Blebbistatin is a potential photodynamic agent that can kill cancer cells. Exposure to UV light with a wavelength below 488nm can also lead to rapid inhibition of Blebbistatin ^[4].

In vitro, (-)-Blebbistatin (10-200μM) was used to treat five human cell lines, including F11-hTERT, U87, Du145, FEMX-I, and LNCaP, for 24h, which inhibited cell viability in a concentration-dependent manner. At the highest dose of 200μM, the survival rates of F11-hTERT cells were approximately 20%, U87 cells were 30%, and Du145, FEMX-I, and LNCaP cells were all below 10%^[5]. Treatment with (-)-Blebbistatin (10μM) on intact and skinned isolated rat heart trabeculae, intact rat cardiomyocytes, and single rabbit psoas myofibrils reduced twitch force and cell shortening, decreased the contractility of trabeculae with intact membranes, without affecting tension-dependent myofilament ATPase activity^[6].

References:
[1] Lucas‐Lopez C, Patterson S, Blum T, et al. Absolute Stereochemical Assignment and Fluorescence Tuning of the Small Molecule Tool,(–)‐Blebbistatin[J]. 2005.
[2] Limouze J, Straight A F, Mitchison T, et al. Specificity of blebbistatin, an inhibitor of myosin II[J]. Journal of Muscle Research & Cell Motility, 2004, 25: 337-341.
[3] Watanabe M, Yumoto M, Tanaka H, et al. Blebbistatin, a myosin II inhibitor, suppresses contraction and disrupts contractile filaments organization of skinned taenia cecum from guinea pig[J]. American Journal of Physiology-Cell Physiology, 2010, 298(5): C1118-C1126.
[4] Sakamoto T, Limouze J, Combs C A, et al. Blebbistatin, a myosin II inhibitor, is photoinactivated by blue light[J]. Biochemistry, 2005, 44(2): 584-588.
[5] Mikulich A, Kavaliauskiene S, Juzenas P. Blebbistatin, a myosin inhibitor, is phototoxic to human cancer cells under exposure to blue light[J]. Biochimica et Biophysica Acta (BBA)-General Subjects, 2012, 1820(7): 870-877.
[6] Farman G P, Tachampa K, Mateja R, et al. Blebbistatin: use as inhibitor of muscle contraction[J]. Pflügers Archiv-European Journal of Physiology, 2008, 455(6): 995-1005.

(-)-Blebbistatin是外消旋体混合物(±)-Blebbistatin（货号：GC12341）的一种其中一个构型，是活性形式。(-)-Blebbistatin是一种非肌肉肌球蛋白II ATP酶的细胞渗透性抑制剂，有效抑制多种横纹肌肌球蛋白以及脊椎动物非肌肉肌球蛋白，IC₅₀值范围为0.5-5μM，平滑肌肌球蛋白仅受到微弱抑制（IC₅₀=80μM）^{[1, 2]}。(+)-Blebbistatinb对各类肌球蛋白II的ATP酶活性、培养平滑肌的细胞迁移无影响^[3]。Blebbistatin是一种潜在的光动力药物，可以杀死癌细胞，暴露于波长低于488nm的UV光也可导致Blebbistatin迅速被抑制^[4]。

在体外，(-)-Blebbistatin（10-200μM）处理F11-hTERT、U87、Du145、FEMX-I、LNCaP等5种人类细胞系24h，浓度依赖性地抑制了细胞活力，最高剂量200μM处理下，F11-hTERT细胞存活率约为20%，U87细胞为30%，Du145、FEMX-I和LNCaP细胞均低于10%^[5]。(-)-Blebbistatin（10μM）处理完整和去皮的分离大鼠心脏小梁、大鼠完整肌细胞和单个兔腰肌肌原纤维，减少了抽搐力和细胞缩短，降低了带皮小梁的收缩力，而不影响张力依赖性肌丝ATP酶活性^[6]。