Chemical Biology REU - Biophysical Chemistry
Advisor
Dr. Lauren Buchanan
Institution
Vanderbilt University
Department
Chemistry
Time
10 weeks - Summer 2024
Background
What is Vibrational Spectroscopy?
Vibrational spectroscopy uses infrared, near-infrared and Raman scattering to measure vibrational frequencies between bonded atoms.
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What is 2D IR Spectroscopy?
Two-dimensional infrared spectroscopy (2D IR) is a spectroscopic tool with increased structural sensitivity over linear IR methods and unique cross peaks that indicate coupled modes.
What is Transition Dipole Strength?
2D IR is also used to calculate transition dipole strength (TDS), which quantifies vibrational coupling and delocalization of vibrational modes.TDS values are particularly useful for distinguishing spectrally similar molecules, such as polymorphs of the same peptide. 2D IR and TDS calculations are broadly applicable to peptide structure and dynamics studies in both small peptides, and complex protein systems with β-sheets, α-helices, and disordered proteins.
Determining Insulin Aggregation Kinetics and Dipeptide Terminal Capping Effects Using 2D IR Spectroscopy and Amide I Transition Dipole Strength
​In this study, I used 2D IR to investigate how sequence variations in insulin II, a mouse homologue of the human insulin gene, can affect its aggregation kinetics. After two and a half hours, the transgenic insulin (B:9-23) variants demonstrated complete aggregation into β-sheets fibrils (LYLAEV mutant and E21A mutant), and aggregation into partial α-helices (short 6.9HIP mutant). In addition, using solid-phase synthesis and high-performance liquid chromatography, I synthesized four dialanines with various terminal groups. For this part of my project, I was analyzing the stabilization and reduced-charge effects of post-translational protein modifications such as N-terminal acetylation and C-terminal amidation. These precise studies of molecular interactions demonstrate the advantages of 2D IR in peptide-based studies over other linear methodologies.
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Techniques and Skills Developed:
Solid-Phase Synthesis​
Mass Spectrometry
HPLC Purification of Proteins
2D IR Use and Data Analysis
