File Name : figure-s1.pdf

Caption : figure s1: a. aligned sequence of r1 and r2. the mutation a32w are highlight in yellow. the residues that are within 5å from retinal with binding are colored in red font. b. the 3d structure of the rhodopsin mimics. the structure in dark blue is the retinal, the bright yellow part is the residues less than 5å away from the retinal after binding with the protein, and the mutation a32w is colored in cyan. notably, the a32w is also within 5å from the retinal.

File Name : figure-s2.pdf

Caption : figure s2: schematic diagram of the experiment. a. schematic diagram of rhodopsin mimic structure. b. schematic diagram of sample purity detected by electrophoresis, where bands 3 and 5 are purified r1 protein bands and 4 and 6 are purified r2 protein bands, both of which meet the experimental requirements. c. schematic diagram of the terahertz absorption measurement on the solid tablet sample. 

File Name : figure-s3.pdf

Caption : figure s3 schematic diagram of root mean square deviation (rmsd) of rhodopsin mimics. figure a-c: schematic diagram of rmsd of protein r1. figure d-f: schematic diagram of rmsd of protein r2. figure g-i: schematic diagram of rmsd of protein r1 after binding with retinal. figure j-l: schematic diagram of rmsd of protein r2 after binding with retinal. in each diagram, the equilibrium region marked by the blue dashed line represents the trajectory file section used for calculating the dipole moment autocorrelation function.

File Name : figure-s4.pdf

Caption : figure s4: terahertz time-domain spectra of rhodopsin mimics with thickness of 0.5mm and 0.65mm. a. terahertz time domain spectra of r1. b. terahertz time-domain spectra of r1 with retinal binding. c. terahertz time domain spectra of r2. d. terahertz time domain spectra of r2 with retinal binding.

File Name : figure-s5.pdf

Caption : figure s5: terahertz time-domain spectra of the n2 and reference ptfe of different thicknesses. a. terahertz time-domain spectra of the reference material ptfe used in the experiment on r1. b. terahertz time-domain spectra of the reference material ptfe used in the experiment on r2.

File Name : figure-s6.pdf

Caption : figure s6: relative refractive indices of r1 and r2 samples with different thicknesses before and after binding with retinal, with the shaded area representing the standard deviation from three independent measurements.

File Name : figure-s7a.pdf

Caption : figure s7: a: vibration direction of r1 protein at different eigenfrequencies without and with retinal binding.

File Name : figure-s7b.pdf

Caption : figure s7. b: vibration direction of r2 protein at different eigenfrequencies without and with retinal binding. (the gray part represents the protein vibration trajectory, while the dark blue part represents the mutation sites of two proteins).

File Name : figure-s8.pdf

Caption : figure s8: comparison of rmsf differences (δrmsf=rmsf with retinal binding-rmsf without retinal binding) between r1 and r2. the x-axis represents the residue number, while the y-axis shows δrmsf (in nm). the black data line corresponds to the results for r1, and the red data line represents the results for r2. rmsf values were derived from three independent md simulations, averaged over the last 100 ns of the equilibrated trajectory.