Disulfide linkage Raman markers: a reconsideration attempt

Abstract

During the last decades, Raman spectroscopy has been routinely used for probing the conformational features of disulfide linkages in peptides and proteins. However, the interpretation of disulfide Raman markers is currently performed by a simple rule derived from the earliest observations on dialkyl disulfides. More precisely, this rule consists of the following: (1) in analyzing the Raman bands in the 550–500 cm−1 region ascribed to disulfide bond stretch motion, namely, ν(S‐S), and (2) assigning the three types of Raman markers observed at ~500, ~520, and ~540 cm−1 to three families of rotamers defined along the three successive bonds of the ‐C‐S‐S‐C‐ moiety, referred to as ggg, ggt, and tgt. In this report, we attempt to show that an accurate analysis of disulfide vibrational features needs the use of the five torsion angles (χ1, χ2, χ3, χ2', and χ1') along the five successive bonds joining the two α‐carbon atoms in the cystine (Cys‐Cys) unit. The present work is inspired by the disulfide conformational investigations performed by a statistical scan of numerous protein crystal and nuclear magnetic resonance data, taking into account the handedness (right and left) of a disulfide bridge, its spatial shape (Staple, Hook, and Spiral), as well as the signs of the two extreme torsion angles χ1 and χ1'. It appears that the combined use of the old and recent conformational notations allows a more accurate structural and vibrational analysis of disulfide linkage. Copyright © 2014 John Wiley & Sons, Ltd.

Self‐healing polyurethane based on disulfide bond and hydrogen bond

“…At the same time, Raman spectroscopy measurements aimed to achieve possible changes in the disulfide content at different samples as shown in Figure . Two spectral bands were ν (S―S) band at 510 cm −1 and ν (C―S) band at 640 cm −1 indicating the existence of disulfide bonds in synthesized self‐healing polyurethane …”

“…Two spectral bands were ν (S-S) band at 510 cm −1 and ν (C-S) band at 640 cm −1 indicating the existence of disulfide bonds in synthesized self-healing polyurethane. 24,25 The peak area was calculated using a peak analyzer tool from Origin software, the baseline was subtracted, and the peak was fitted in Gaussian function and shown in Table 1. The area under the curve peak corresponding to the characteristic bands is expected to be proportional to the respective bond concentration.…”

A Novel Self‐Healing Polyurethane Based on Disulfide Bonds

“…To capture the evidences of disulfide bonds, Raman spectra of synthesized samples were obtained and showed in Figure a. Most parts of the spectra were identical except that the v(s–s) band at 508 cm −1 and the v(c–s) band at 640 cm −1 were only observed for PU‐A, therefore, indicating the existence of disulfide bonds in PU‐A.…”

Self‐Healable and Mechanically Reinforced Multidimensional‐Carbon/Polyurethane Dielectric Nanocomposite Incorporates Various Functionalities for Capacitive Strain Sensor Applications

“…Figure b displayed the Raman spectra of pure SHPU, SHPU‐GC, and SHPU‐RGC. The characteristic peaks of SS bond at 498 cm −1 and CS at 640 cm −1 were observed in the Raman spectrum of SHPU, indicating the existence of disulfide bonds in the as‐prepared polyurethane . However, the characteristic peaks apart from D and G bonds disappeared completely after the addition of GC, which shows that the fillers dominated over polyurethane in the Raman spectra of SHPU‐GC and SHPU‐RGC.…”

“…The characteristic peaks of SS bond at 498 cm −1 and CS at 640 cm −1 were observed in the Raman spectrum of SHPU, indicating the existence of disulfide bonds in the as-prepared polyurethane. [40] However, the characteristic peaks apart from D and G bonds disappeared completely after the addition of GC, which shows that the fillers dominated over polyurethane in the Raman spectra of SHPU-GC and SHPU-RGC. The G-bond of SHPU-RGC occurred at 1581 cm −1 compared with that of SHPU-GC (1595 cm −1 ), which corresponded to the recovery of the hexagonal network of carbon atoms with defects.…”