SDS-PAGE analysis of purified monomeric and cross-linked Rv0091. Rv0091 was purified to homogeneity, and SDS-PAGE analysis revealed a band consistent with the predicted mass (29.4 kDa) of the monomeric protein. The pure protein was treated with 0.1% to 2% glutaraldehyde to allow for intersubunit cross-linking. A band consistent with a dimeric oligomerization state was observed for the cross-linked protein. Lane 1, protein molecular weight standards; lane 2, Rv0091 + 0.1% glutaraldehyde; lane 3, Rv0091 + 0.5% glutaraldehyde; lane 4, Rv0091 + 2% glutaraldehyde; lane 5, Rv0091 before cross-linking.