Synthesis and Photophysical Characterization of a New, Highly Hydrophilic Caging Group

Abstract

o-Nitrobenzyl-protected bioactive compounds are useful tools in biophysics, allowing controlled photorelease of biologically active compounds with high temporal and spatial precision. Thus, it is possible to study biological processes, such as neurotransmitter-receptor interaction, and many other processes, in much more detail than before. In this respect, these caged compounds have become established as extremely useful tools. In some cases, however, their biological properties (the caged compound should not interact with the biological system), their photochemical properties (quantum yield and kinetics of the photorelease), and their physical properties (high hydrophilicity) are not satisfactory. In order to address the last problem, we examined means to increase the hydrophilicity of caged compounds based on the o-nitrobenzyl moiety. Here, we report the synthesis and the photochemical and biological characterization of a new caged D-aspartate derivative with vastly improved hydrophilicity, compared to derivatives reported previously, and satisfactory photophysical properties. Caged compounds with this improved o-nitrobenzyl group may thus represent a valuable new tool for different kinds of biophysical investigations. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)