Assembly and stoichiometry
The self- and co-assembly of proteins underpins their biological function, while protein aggregation can lead to ineffective function, or even toxicity. Mass photometry provides a unique means to measure the mass distribution of proteins, detecting quantitatively even very rare stoichiometries, in solution. This provides an unparalleled view of the composition of a protein solution, and an avenue to test and optimise solution conditions that may influence oligomerization or aggregation.
Mass photometry allows the determination of stoichiometry distributions of proteins. During a mass photometry experiment, the signal corresponding to individual protein landing events are detected independently from those of others. Single particle detection delivers a high dynamic range (3 orders of magnitude in this spectrum) and the ability to detect low abundance species, such as bovine serum albumin (BSA) tetramers (0.25%). The polydispersity of BSA (67 kDa monomer) is baseline-resolved and the relative amounts of monomer, dimer, trimer and tetramer can be quantified directly from the number of landing events.
Data from Young et al, Science, 2018, 360 (6387), p423-7.