Using a quantum mechanical/molecular mechanical approach, we show the mechanisms of how the protein environment of Guillardia theta anion channelrhodopsin-1 (GtACR1) can shift the absorption wavelength. The calculated absorption wavelengths for GtACR1 mutants, M105A, C133A, and C237A are in agreement with experimentally measured wavelengths. Among 192 mutant structures investigated, mutations at Thr101, Cys133, Pro208, and Cys237 are likely to increase the absorption wavelength. In particular, T101A GtACR1 was expressed in HEK293T cells. The measured absorption wavelength is 10 nm higher than that of wild type, consistent with the calculated wavelength. (i) Removal of a polar residue from the Schiff base moiety, (ii) addition of a polar or acidic residue to the β-ionone ring moiety, and (iii) addition of a bulky residue to increase the planarity of the β-ionone and Schiff base moieties are the basis of increasing the absorption wavelength.

使用量子力学/分子力学方法，我们展示了Guillardia theta阴离子通道视紫红质-1（Gt ACR1）的蛋白质环境如何改变吸收波长的机制。Gt ACR1突变体M105A，C133A和C237A的计算吸收波长与实验测量的波长一致。在研究的192个突变体结构中，Thr101，Cys133，Pro208和Cys237处的突变可能会增加吸收波长。特别是T101A GtACR1在HEK293T细胞中表达。测得的吸收波长比野生型高10 nm，与计算的波长一致。（i）从席夫碱部分去除极性残基，（ii）向β-紫罗兰酮环部分添加极性或酸性残基，以及（iii）添加大块残基以增加β-紫罗兰酮的平面度席夫碱部分和席夫碱部分是增加吸收波长的基础。