*4.2. Intrinsic Tryptophan Fluorescence Spectroscopy*

Intrinsic tryptophan fluorescence spectra were obtained using an Applied Photophysics qCD Chirascan equipped with a fluorimeter at ambient temperature using cuvettes with a path length of 1 cm. Samples were run with an excitation wavelength of 280 nm, an excitation bandwidth of 5 nm, boxcar width of 5 nm, and averaged over 10 scans, with each scan taking 1 s. All mAb samples were diluted to approximately 0.033 mg/mL with buffer before measurements. Each sample was measured in triplicate and buffer blanks were subtracted before data analysis. The spectra were overlaid with each other and the similarity was compared by calculating the variability of the maximum fluorescence intensity and the wavelength at the maximum fluorescence.
