Mass spectra of fractions 30 and 31 obtained after digestion of the patient sample protein C light chain with endoproteinase Asp-N (see Fig 3). The explanation of the values around m/z = 4,400 are discussed in the text. The peaks m/z = 2,329 and 2,257 are most likely the doubly charged species. There is no obvious explanation of the peaks with m/z = 3,545 and 3,547. m/z denotes ratio between mass of the molecular ion and charge, whereas a.i. denotes number of accumulated ions.