YANG Yun-fan1, HU Jian-bo1, LIU Yong-gang1，2*, LIU Qiang-qiang3, ZHANG Hang4, XU Jian-jie5, GUO Teng-xiao5
1. State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China
2. China Academy of Engineering Physics Research Center of Laser Fusion，Mianyang 621010, China
3. School of Chemistry and Environmental Engineering, Sichuan University of Science & Engineering, Zigong 643002, China
4. Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
5. State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
Abstract：Peptides are important biological molecules. Ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy are important methods for studying the fine structure of biomolecules. The structures and molecular frontier orbital of Growth hormone-releasing peptide (GHRP-6) and Oxytocin were calculated by density functional theory (DFT/RI). Based on time-dependent density functional theory (TDDFT), TDA and other parameter approximations are introduced to establish theoretical models for calculating the UV-Vis and fluorescence spectra of peptides. For GHRP-6, UV spectrum peak is λcal.=282 nm (λExp.=279 nm, Δλ=3 nm, Er＜2%), and fluorescence spectrum peak is λcal.=368 nm (λExp.=360 nm, Δλ=8 nm, Er＜3%). For Oxytocin, UV spectrum peak is λcal.=269 nm (λExp.=275 nm, Δλ=6 nm, Er＜3%), and fluorescence spectrum peak is λcal.=305 nm (λExp.=312 nm, Δλ=7 nm, Er＜3%). The fluorescence emission wavelength produced by GHRP-6 is similar to the fluorescence wavelength range produced by tryptophan, indicating that the main contribution of GHRP-6 fluorescence is the π*→π orbital transition on the tryptophan residue, Oxytocin fluorescence peak position is similar to the fluorescence wavelength range produced by tyrosine. The main contribution of Oxytocin’s fluorescence is the π*→π orbital transition on tyrosine residues. Calculation results obtain via theoretical models are in good agreement with the experimental. It shows that the models are feasible to accurately calculate the UV Vis absorption spectra and fluorescence spectra of polypeptides, providing reliable theoretical guidance for experiments.
杨云帆，胡建波，刘永刚，刘强强，张 航，徐建洁，郭腾霄. 基于密度泛函理论下多肽光谱性质研究[J]. 光谱学与光谱分析, 2021, 41(10): 3172-3177.
YANG Yun-fan, HU Jian-bo, LIU Yong-gang, LIU Qiang-qiang, ZHANG Hang, XU Jian-jie, GUO Teng-xiao. DFT／TDDFT Study on Spectra of Peptides. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(10): 3172-3177.
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