Theoretical Chemistry Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen 9747AG, The Netherlands.
J Phys Chem B. 2021 Mar 11;125(9):2231-2240. doi: 10.1021/acs.jpcb.0c10466. Epub 2021 Feb 24.
Infrared fluorescent proteins (iRFPs) are potential candidates for deep-tissue in vivo imaging. Here, we provide molecular-level insights into the role of the protein environment in the structural stability of the chromophore within the protein binding pocket through the flexible hydrogen-bonding network using molecular dynamics simulation. Furthermore, we present systematic excited-state analysis to characterize the nature of the first two excited states and the role of the environment in shaping the nature of the chromophore's excited states within the hybrid quantum mechanics/molecular mechanics framework. Our results reveal that the environment red-shifts the absorption of the chromophore by about 0.32 eV compared to the isolated counterpart, and besides the structural stability, the protein environment does not alter the nature of the excited state of the chromophore significantly. Our study contributes to the fundamental understanding of the excited-state processes of iRFPs in a complex environment and provides a design principle for developing iRFPs with desired spectral properties.
红外荧光蛋白（iRFPs）是用于深层组织体内成像的潜在候选者。在这里，我们通过分子动力学模拟，提供了分子水平上的见解，了解了蛋白质结合口袋内的发色团在蛋白质环境中的结构稳定性中的作用，通过灵活的氢键网络。此外，我们提出了系统的激发态分析，以在混合量子力学/分子力学框架内表征前两个激发态的性质以及环境在塑造发色团激发态性质中的作用。我们的结果表明，与孤立的对应物相比，环境将发色团的吸收红移了约 0.32eV，除了结构稳定性之外，蛋白质环境不会显著改变发色团激发态的性质。我们的研究有助于深入了解复杂环境中 iRFPs 的激发态过程，并为开发具有所需光谱特性的 iRFPs 提供了设计原则。
