Summary
This study sequenced and characterized all five visual opsin genes in the red-eared slider turtle, predicting peak absorption wavelengths (λmax) using amino acid sequences and computational models. While the findings are primarily of basic science interest, the established calibration curves for vitamin A2-based chromophore shifts and validated λmax prediction methods could inform broader understanding of spectral sensitivity in vertebrate photoreceptors.
Key Findings
- Estimated λmax values based on amino acid spectral tuning residues closely matched prior microspectrophotometry data: SWS1 = 374 nm, SWS2 = 456 nm, RH1 = 518 nm, RH2 = 519 nm, LWS = 617 nm
- Computational (TD-DFT) models were accurate for rhodopsin (517 nm) but showed deviations for cone opsins: SWS1 = 400 nm, SWS2 = 437 nm, RH2 = 500 nm, LWS = 627 nm
- Use of the 3,4-dehydroretinal (vitamin A2) chromophore causes a bathochromic (red) shift in λmax, and a calibration equation was developed to correct for this shift across opsin classes
- All five computational protein models had >90% of amino acids in highly favorable regions of the Ramachandran plot, indicating good structural quality
Categories
The Science of Light: This study analyzes the genetic and molecular basis of visual pigments (opsins) in a vertebrate species, characterizing spectral sensitivity and peak absorption wavelengths across all five opsin classes.
Author(s)
VH Corredor
Publication Year
2020
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