No abstract

Protein secondary structures are frequently assessed using infrared and circular dichroism spectroscopies during drug development (e.g., during product comparability and biosimilarity studies, reference standard characterization, etc.) However, there is little information on the lower limits of quantitation of structural misfolds and impurities for these methods. A model system using a monoclonal antibody reference material was spiked at various levels with a protein that had a significantly different secondary structure to represent the presence of a stable and discreet structural misfold. The ability of circular dichroism, transmission Fourier transform infrared spectroscopy and microfluidic modulation spectroscopy, along with various spectral comparison algorithms, were assessed for their ability to detect the presence and quantify the amount of the misfolded structure.

Detailed investigation on the vibrational and electronic spectra has been carried out in order to study various properties of bis(2-thienyl)ketone molecule in its ground and excited electronic states. To get insight into the structural and symmetry features of the molecule, resonance Raman spectra (RRs) of bis(2-thienyl)ketone have been acquired and the Raman excitation profiles of several normal modes have been analyzed, and density functional calculations were done to help the elucidation of the photo relaxation dynamics of A and B band electronic transitions. The RRs indicate that the photo relaxation dynamics for S(0)→S(2) excited electronic state is predominantly along the nominal the Ring breathing + ν(SynC(1)C(11) C(9)) stretch, ν(CO) + ν(C(2)C(3)) + ν(C(8)C(9)) stretch, and the γ(CH(I, II)) + γ(OC) stretch and simultaneously along the nominal γ(CH(II)) relaxation processes, while that for S(0)→S(5) is predominantly along the ν(CO) + ν(C(2)C(3)) + ν(C(8)C(9)) stretch ν(7) (1616 cm(-1)). The excited state short-time structural dynamics of bis (2-thienyl) ketone determined from RRs were interpreted with account of the Albrecht's theory and Herzberg-Teller contributions.