Practice question

Oligomeric state assessment by mass spectrometry compares observed mass to theoretical monomer mass. Monomeric protein yields dominant peak near expected mass M for singly charged ion, with possible charge envelope for electrospray. Noncovalent dimerization or disulfide-linked dimer doubles molecular weight, producing additional signal near 2M, sometimes with its own charge series. Observing half mass would indicate doubly charged monomer or proteolytic fragment, single peak suggests pure monomer, triplet pattern often signals isotopic distribution or chlorine adducts. Detection of double-mass species informs studies of protein aggregation, receptor dimerization and amyloid assembly.