Ultrasensitive Detection and Characterization of Posttranslational Modifications Using Surface-Enhanced Raman Spectroscopy

Abstract

Posttranslational modification (PTM) of proteins is likely to be the most common mechanism of altering the expression of genetic information. It is essential to characterize PTMs to establish a complete understanding of the activities of proteins. Here, we present a sensitive detection method using surface-enhanced Raman spectroscopy (SERS) that can detect PTMs from as little as zeptomoles of peptide. We demonstrate, using model peptides, the ability of SERS to detect a variety of protein modifications, such as acetylation, trimethylation, phosphorylation, and ubiquitination. In addition, we show the capability to obtain positional information for modifications such as trimethylation and phosphorylation using SERS and wavelet decomposition data analysis techniques. We further show that it is possible to apply SERS to detect PTMs from biological samples such as histones. We envision that this detection method might be a valuable technique that is complementary to mass spectrometry in obtaining orthogonal chemical and modification-specific information from biological samples at sensitive levels.

Detection of Receptor-Induced Glycoprotein Conformational Changes on Enveloped Virions by Using Confocal Micro-Raman Spectroscopy

“…For example, Raman spectroscopic methods have been used to investigate protein structure (57); alpha-helix hydration in polypeptides, proteins, and viruses (58-62); polypeptide and carbohydrate structures of glycoproteins (63); carbohydrate characterization (64); and the molecular structures of proteins (62,63,(65)(66)(67). Raman spectroscopy has been validated as a highly accurate and reliable method to monitor and determine protein secondary structural variations in situ, such as folding and orientation (68,69), glycosylation status (43), phosphorylation status (42,70), and posttranslational modifications (71). The overall secondary structures of the glycosylated and deglycosylated forms of soluble glycoprotein C of herpes simplex virus were differentiated by using conventional Raman spectroscopy (72).…”

Raman spectroscopy and microscopy of individual cells and cellular components

“…This property is expected to work just as well for deep-tissue imaging in-vivo. Other applications are expected from the use of bioactive nanoprobes that might be able to, for example, detect post-translational protein modifications in-vivo [137]. Additional benefits might arise from the combination of SERS nanoprobes with CARS microscopy, which should provide superior bleaching-resistant sensitivity for in-vivo sensing compared to any other optical probe.…”

Raman Micro-Spectroscopy for Rapid Screening of Oral Squamous Cell Carcinoma

“…histone modification, DNA methylation. The sensitivity of the analysis used in this study is unlikely to identify such specific changes in cells, but both posttranslational modification and epigenetic changes have been observed utilizing surface-enhanced Raman spectroscopy (Barhoumi & Halas, 2011;Sundararajan et al 2006) and variation between the cell types used are potentially the result of an accumulation of these cellular changes (>75%). Notably, however, more sophisticated multivariate classification techniques can be applied to achieve higher degrees of sensitivity and specificity for real clinical applications (Lasalvia et al, 2015;Knipfer et al, 2014;Lyng et al, 2007).…”