Deciphering the Molecular Dance: Exploring the Dynamic Interplay Between Mouse Insulin B9-23 Peptides and their Variants.

Type 1 diabetes results from the autoimmune destruction of pancreatic insulin-producing β-cells, primarily targeted by autoreactive T cells that recognize insulin B9-23 peptides as antigens. Using drift tube ion mobility spectrometry-mass spectrometry, transmission electron microscopy, and two-dimensional infrared spectroscopy, we characterized mouse insulin 1 B9-23 (Ins1 B9-23), insulin 2 B9-23 (Ins2 B9-23), along with two of their mutants, Ins2 B9-23 Y16A and Ins2 B9-23 C19S. Our findings indicate that Ins1 B9-23 and the Ins2 Y16A mutant exhibit rapid fibril formation, whereas Ins2 B9-23 and the Ins2 C19S mutant show slower fibrillization and a structural rearrangement from globular protofibrils to fibrillar aggregates.

Suppressing sidechain modes and improving structural resolution for 2D IR spectroscopy via vibrational lifetimes.

Vibrational spectroscopy of protein structure often utilizes 13C18O-labeling of backbone carbonyls to further increase structural resolution. However, sidechains such as arginine, aspartate, and glutamate absorb within the same spectral region, complicating the analysis of isotope-labeled peaks. In this study, we report that the waiting time between pump and probe pulses in two-dimensional infrared spectroscopy can be used to suppress sidechain modes in favor of backbone amide I' modes based on differences in vibrational lifetimes.

Probing local changes to α-helical structures with 2D IR spectroscopy and isotope labeling.

α-Helical secondary structures impart specific mechanical and physiochemical properties to peptides and proteins, enabling them to perform a vast array of molecular tasks ranging from membrane insertion to molecular allostery. Loss of α-helical content in specific regions can inhibit native protein function or induce new, potentially toxic, biological activities. Thus, identifying specific residues that exhibit loss or gain of helicity is critical for understanding the molecular basis of function.

Determining the impact of gold nanoparticles on amyloid aggregation with 2D IR spectroscopy.

As nanomaterials become more prevalent in both industry and medicine, it is crucial to fully understand their health risks. One area of concern is the interaction of nanoparticles with proteins, including their ability to modulate the uncontrolled aggregation of amyloid proteins associated with diseases, such as Alzheimer's disease and type II diabetes, and potentially extend the lifetime of cytotoxic soluble oligomers. This work demonstrates that two-dimensional infrared spectroscopy and CO isotope labeling can be used to follow the aggregation of human islet amyloid polypeptide (hIAPP) in the presence of gold nanoparticles (AuNPs) with single-residue structural resolution.