Rossi F M, Margulis M, Tang C M, Kao J P
Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201, USA.
J Biol Chem. 1997 Dec 26;272(52):32933-9. doi: 10.1074/jbc.272.52.32933.
We report the synthesis, the physicochemical characterization, and biological evaluation of a new caged glutamate, N-(o-nitromandelyl)oxycarbonyl-L-glutamic acid (Nmoc-Glu), that liberates free glutamate on photolysis. The low affinity of certain glutamate receptors and their rapid entry into desensitization have effectively prevented the creation of an ideal caged glutamate. In the absence of an ideal compound, Nmoc-Glu was designed to resist spontaneous hydrolysis while maintaining reasonable photorelease yield and kinetics. Chemical and physiological analyses reveal that Nmoc-Glu, indeed, has exceptionally low residual activity and high chemical stability. The quantum yield of Nmoc-Glu is 0.11. Photolytic uncaging and release of free glutamate occur in two steps, consisting of an initial light-induced cleavage that proceeds on the sub-millisecond time scale, and a subsequent light-independent, pH-dependent decarboxylation step that proceeds on the millisecond time scale. The low residual activity and high chemical stability of Nmoc-Glu are important advantages in applications where pre-photolysis Glu receptor activation and desensitization must be minimized.
我们报道了一种新型笼形谷氨酸N-(邻硝基扁桃酰基)氧羰基-L-谷氨酸（Nmoc-Glu）的合成、理化特性及生物学评价，该化合物在光解时可释放出游离谷氨酸。某些谷氨酸受体的低亲和力及其迅速进入脱敏状态，有效地阻碍了理想笼形谷氨酸的产生。在缺乏理想化合物的情况下，设计Nmoc-Glu以抵抗自发水解，同时保持合理的光释放产率和动力学。化学和生理学分析表明，Nmoc-Glu确实具有极低的残余活性和高化学稳定性。Nmoc-Glu的量子产率为0.11。游离谷氨酸的光解解笼和释放分两步进行，包括在亚毫秒时间尺度上进行的初始光诱导裂解，以及在毫秒时间尺度上进行的随后的光独立、pH依赖的脱羧步骤。在必须将光解前谷氨酸受体激活和脱敏降至最低的应用中，Nmoc-Glu的低残余活性和高化学稳定性是重要优势。
