Suc-Leu-Tyr-AMC, a fluorescent substrate for calpain I and II and papain (cysteine protease) measuring the chymotrypsin-like peptidase activity of the 20S proteasome, emits bright fluorescence has been used extensively for calpain I and II and papain evaluation (Ex/Em: 360/460nm) . Suc-Leu-Tyr-AMC causes a complete inhibition of casein breakdown at high concentrations that are regulated by Na+ and K+ in vivo[1,2]. Suc-Leu-Tyr-AMC is widely applied in calpain activity analysis in vitro[3]. Suc-Leu-Tyr-AMC can not be applied in live cells or in vivo, only extracellular calpain assay (in vitro or ex vivo) was applied.
Suc-Leu-Tyr-AMC is used to evaluate calpain activity with rat liver IMS protein (20μM; 20min incubation; 25°C)[4], fibrillating human atria lysate (125μM; 10min incubation; 37°C)[5], Mouse C2C12 myoblasts lysate (40mM; 30min; room temperature)[6] with extracted materials such as extracted proein and cell or tissue lysate.
References:
[1] Woo, K M et al. “Protease Ti from Escherichia coli requires ATP hydrolysis for protein breakdown but not for hydrolysis of small peptides.” *The Journal of biological chemistry* vol. 264,4 (1989): 2088-91.
[2] Seol, J H et al. “Na+, K+-specific inhibition of protein and peptide hydrolyses by proteasomes from human hepatoma tissues.” *FEBS letters* vol. 247,2 (1989): 197-200. doi:10.1016/0014-5793(89)81333-x
[3] Ozaki, Taku et al. “Characteristics of mitochondrial calpains.” *Journal of biochemistry* vol. 142,3 (2007): 365-76. doi:10.1093/jb/mvm143
[4] Ozaki, Taku et al. “Intravitreal injection or topical eye-drop application of a μ-calpain C2L domain peptide protects against photoreceptor cell death in Royal College of Surgeons' rats, a model of retinitis pigmentosa.” *Biochimica et biophysica acta*vol. 1822,11 (2012): 1783-95. doi:10.1016/j.bbadis.2012.07.018
[5] Goette, Andreas et al. “Calpains and cytokines in fibrillating human atria.” *American journal of physiology. Heart and circulatory physiology* vol. 283,1 (2002): H264-72. doi:10.1152/ajpheart.00505.2001
Liao, Zhiyin et al. “CHRNA1 induces sarcopenia through neuromuscular synaptic elimination.” *Experimental gerontology* vol. 166 (2022): 111891. doi:10.1016/j.exger.2022.111891
Suc-Leu-Tyr-AMC是一种测量20S蛋白酶体凝乳胰蛋白酶样肽酶活性的calpain I和II和papain（半胱氨酸蛋白酶）荧光底物，发出明亮的荧光，已广泛用于calpain I和II和pap蛋白酶的评价（激发/发射光：360/460nm）。在体内，Suc-Leu-Tyr-AMC在高浓度下完全抑制酪蛋白分解，酪蛋白分解受Na+和K+调节[1,2]。Suc-Leu-Tyr-AMC广泛应用于体外钙蛋白酶活性分析。Suc-Leu-Tyr-AMC不能在活细胞或体内应用，只能应用细胞外钙蛋白酶测定（体外或离体实验）[3]。
Suc-Leu-Tyr-AMC用大鼠肝脏IMS蛋白（20μM; 20分钟; 25°C）[4]、人心房纤原裂解液（125μM; 10分钟; 37°C）[5]、小鼠C2C12成肌细胞裂解液（40mM; 30min; 室温）[6]和提取物（提取蛋白和细胞或组织裂解液）评价calpain活性。