State-by-State Investigation of Destructive Interference in Resonance Raman Spectra of Neutral Tyrosine and the Tyrosinate Anion with the Simplified Sum-over-States Approach

UV–Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 1: basic principles and properties of tyrosine chromophore

“…Figure 11 presents resonance Raman scattering spectra for Tyr in water with 229 and 244 nm laser excitation, one at neutral pH and the other at pH 13, causing ionization of the Tyr hydroxyl group, obtained by Cabalo et al ( 2014 ).

Fig.

…”

“…11 Experimental RRS spectra with 229- and 244-nm laser excitation of tyrosine in neutral and basic aqueous solutions. Figure based on experimental data, in numerical form, kindly provided by Cabalo et al ( 2014 ) …”

All characteristic Raman markers of tyrosine and tyrosinate originate from phenol ring fundamental vibrations

“…[17] The formation of the Tyr anion, also referred to as tyrosinate, achieved by the phenol ring hydroxyl deprotonation (Scheme 1), has been emphasized for its role in a proton-coupled electron transfer under the action of photosynthetic water oxidase. [18] Vibrational data concerning the Tyr → tyrosinate conversion in aqueous samples, observed upon increasing pH, were recently reported by means of ultraviolet resonance Raman spectra in free Tyr [19] and by classical Raman spectra in an octapeptide. [20] To analyze the structural features and accurately assign the Tyr and tyrosinate characteristic vibrations, modern quantum mechanical calculations generally based on the density functional theory were performed during the recent years.…”

“…[20] To analyze the structural features and accurately assign the Tyr and tyrosinate characteristic vibrations, modern quantum mechanical calculations generally based on the density functional theory were performed during the recent years. [9,[19][20][21][22][23][24][25] Among these calculations, one can distinguish those performed on the neutral (in vacuum) form of free Tyr, [21,22] as well as on its zwitterionic form. [9,19,23] The latter data are evidently more convenient for the interpretation of the aqueous phase experiments.…”

“…[9,[19][20][21][22][23][24][25] Among these calculations, one can distinguish those performed on the neutral (in vacuum) form of free Tyr, [21,22] as well as on its zwitterionic form. [9,19,23] The latter data are evidently more convenient for the interpretation of the aqueous phase experiments. Two recent investigations were devoted to the structural and vibrational analysis of larger size Tyr-containing peptides, such as the tripeptide Gly-Tyr-Gly [24] or the octapeptide Ile-Met-Lys-Lys-Ala-Tyr-GluLeu.…”