An A2M mutant, A2M-3K, with the bait region arginines replaced with lysines, was cross-linked with DSSO. Its monomeric gel band was analyzed by XL-MS to identify the bait region position within a subunit.
Human A2M was cross-linked with DSSO in its native, methylamine-treated, and trypsin-cleaved conformations. The monomer, dimer, and tetramer SDS-PAGE gel bands of native A2M were analyzed by in-gel digest. Total protein digests of all three conformations were analyzed and compared.