Characterization of a few Raman lines of tryptophan

Abstract

The Raman spectrum of tryptophan has been observed in its neutral aqueous solution with 514.5, 488.0, 457.9, 363.8, and 257.3 nm excitation. The effects of N‐deuteration and 15N‐substitution of the indole ring on the Raman spectrum have been examined. A preliminary normal coordinate treatment of the indole ring has also been made. On the basis of these data, the vibrational mode and a possible origin of the Raman scattering intensity has been discussed for each of the 1623, 1555, 1436, 1344, 1016, 882, and 762 cm−1 Raman lines of tryptophan. The resonance enhanced line at 1623 cm−1 has been assigned to a vibration of the indole ring which is related to the b3g ring stretching vibration of naphthalene at 1636 cm−1. Its intensity is considered to come almost solely from the B̃ ← X̃ (La) electronic transition at 273 nm. It is therefore probable that the geometrical structure of the molecule is distorted along this vibrational coordinate on going from the ground (X̃) to the B̃ electronic excited state.

Assignment of the 1511 cm−1 UV resonance Raman marker band of hemoglobin to tryptophan

“…In this experiment 15‐N was incorporated into Hb by expressing the protein in bacteria grown on 15‐NH, and spectra were recorded in D 2 O in order to intensify the histidine signals12; a large 15‐N shift was seen for the 1407 cm −1 band that arises from protonated histidine residues 14. The 2 cm −1 downshift in 2×W18 is consistent with the 1 cm −1 shift, which was reported for the fundamental 15…”

Acquisition of Raman spectra of amino acids using portable instruments: Outdoor measurements and comparison

“…The 1555 cm −1 band is attributed to the degenerate pair of stretching vibrations of the benzene ring by Hirakawa et al [17] and can be found at 1556 cm −1 in our work. According to the work of Hirakawa et al, the strongly coupled benzene and pyrrole ring breathing vibrations give rise to two strong Raman bands located at 1016 and 762 cm −1 .…”

Impact of Solvent on Electrospinning of Zein and Analysis of Resulting Fibers

“…Raman spectra has been used to define the differences in the environment around certain amino acid residues such as tryptophan or tyrosine 31–34. With the differences observed in degree of birefringence and morphology between fibers produced from 80% EtOH/water (Sample G) and AcOH (Sample P) we examined the Raman spectra of the generated fibers.…”