Table S-1: List of MRM-MS assay transitions monitored.

Table S-2:

Sheet 1: Skyline export results for mouse brain homogenate and mouse spinal cord.

Sheet 2: Skyline export results for human olfactory neurosphere-derived stem (ONS) cell.

Sheet 3: Blank subtraction, normalisation, LOD estimation, LOQ estimation and % coefficient of variation calculation of the dataset.

Sheet 4: Calculations for SIL peptide injection along with results of unknown estimation and % acetylation estimation for the dataset.