Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, USA.
Bioorg Med Chem. 2010 Feb 15;18(4):1591-8. doi: 10.1016/j.bmc.2009.12.075. Epub 2010 Jan 6.
Protein kinase C (PKC) is a family of serine/threonine kinases that play a central role in cellular signal transduction. The second messenger diacylglycerol having two long carbon chains acts as the endogenous ligand for the PKCs. Polyphenol curcumin, the active constituent of Curcuma longa is an anti-cancer agent and modulates PKC activity. To develop curcumin derivatives as effective PKC activators, we synthesized several long chain derivatives of curcumin, characterized their absorption and fluorescence properties and studied their interaction with the activator binding second cysteine-rich C1B subdomain of PKCdelta, PKCepsilon and PKCtheta. Curcumin (1) and its C16 long chain analog (4) quenched the intrinsic fluorescence of PKCdeltaC1B, PKCepsilonC1B and PKCthetaC1B in a manner similar to that of PKC activator 12-O-tetradecanoylphorbol 13-acetate (TPA). The EC(50)s of the curcumin derivatives for fluorescence quenching varied in the range of 4-11 microM, whereas, EC(50)s for TPA varied in the range of 3-6 microM. Fluorescence emission maxima of 1 and 4 were blue shifted and the fluorescence anisotropy values were increased in the presence of the C1B domains in a manner similar to that shown by the fluorescent analog of TPA, sapintoxin-D, confirming that they were bound to the proteins. Molecular docking of 1 and 4 with novel PKC C1B revealed that both the molecules form hydrogen bonds with the protein residues. The present result shows that curcumin and its long chain derivatives bind to the C1B subdomain of novel PKCs and can be further modified structurally to improve its binding and activity.
蛋白激酶 C（PKC）是一族丝氨酸/苏氨酸激酶，在细胞信号转导中起着核心作用。具有两条长碳链的第二信使二酰基甘油作为 PKC 的内源性配体。姜黄中的活性成分姜黄素是一种抗癌剂，可调节 PKC 活性。为了开发有效的 PKC 激活剂作为姜黄素衍生物，我们合成了几种姜黄素的长链衍生物，对它们的吸收和荧光特性进行了表征，并研究了它们与激活剂结合的 PKCdelta、PKCepsilon 和 PKCtheta 的第二胱氨酸丰富 C1B 亚域的相互作用。姜黄素（1）及其 C16 长链类似物（4）以类似于 PKC 激活剂 12-O-十四烷酰佛波醇 13-乙酸酯（TPA）的方式猝灭 PKCdeltaC1B、PKCepsilonC1B 和 PKCthetaC1B 的本征荧光。姜黄素衍生物荧光猝灭的 EC（50）值在 4-11μM 范围内变化，而 TPA 的 EC（50）值在 3-6μM 范围内变化。在 C1B 结构域存在的情况下，1 和 4 的荧光发射最大值发生蓝移，荧光各向异性值增加，与 TPA 的荧光类似物 sapintoxin-D 相似，证实它们与蛋白质结合。1 和 4 与新型 PKC C1B 的分子对接表明，这两种分子都与蛋白质残基形成氢键。目前的结果表明，姜黄素及其长链衍生物与新型 PKC 的 C1B 亚域结合，并可进一步进行结构修饰以提高其结合和活性。
