Proteins in solution can adopt multiple conformational states that could be important to function. However, the study of the conformational states of proteins is challenged by the spatial heterogeneity of proteins and the timescales on which they interconvert, which can range from picoseconds to milliseconds and longer. Infrared (IR) spectroscopy is a powerful technique that has an inherently high temporal resolution required to observe these different timescales and bond-specific spatial resolution. However, the use of IR to study proteins has been limited due to the congested spectra of proteins arising from the large number of similarly bonded atoms. Fortunately, there exists within protein spectra a “transparent” frequency window (~1800-2500 cm-1). A vibrational probe with an absorption frequency within this window can be site-selectively incorporated into proteins that is sensitive to its local environment. Carbon-deuterium (C-D) bonds are ideal probes due to their completely non-perturbative nature in proteins. An example of such a probe is d3-L-proline (d3Pro). This probe has been used to investigate molecular recognition of peptides by a Src Homology 3 (SH3) domain, a canonical model of molecular recognition. SH3 domains recognize the motif PxxP, so d3Pro is a useful probe of the recognition sequence. The asymmetric stretch of the CδD2 group of the incorporated d3Pro shows sensitivity to the local conformation of the peptide. Changes in this vibration when the peptides bind to Fyn-SH3 inform on variation in the mechanisms of molecular recognition by the SH3 domain and highlights the importance of conformational heterogeneity in molecular recognition.

Residue specific characterization of proline-rich motif recognition via infrared spectroscopy

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.