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International Journal of Hepatology
Volume 2012, Article ID 369740, 12 pages
Research Article

Characterization of Autoantibodies against the E1 𝜶 Subunit of Branched-Chain 2-Oxoacid Dehydrogenase in Patients with Primary Biliary Cirrhosis

1Department of Human Lifesciences, Fukushima Medical University School of Nursing, 1 Hikarigaoka, Fukushima 960-1295, Japan
2Department of Internal Medicine II, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima 960-1295, Japan
3Structural Glycobiology Team, Systems Glycobiology Research Group, Chemical Biology Department, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
4Department of Biochemistry, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima 960-1295, Japan

Received 1 December 2011; Revised 16 February 2012; Accepted 26 February 2012

Academic Editor: Pierluigi Toniutto

Copyright © 2012 Tsutomu Mori et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Supplementary Material

Figure S1: The Z-score representation of reactivities of PBC sera against synthesized peptides of BCOADC-E1α. To normalize the results of pin ELISA (Figures 2a and 2b), the obtained OD450 values were transformed into Z-scores [25]. The pin number represents the N-terminal amino acid number of each peptide. The location of the major epitope is indicated by blue squares.

Figure S2: Solvent accessible surface areas of BCOADC-E1α. The solvent accessible surface areas of the BCOADC-1α subunit were calculated using the DSSP program ( [26]. Two areas (aa 137-142 and 153-156) within the major determinant region are found to be accessible to solvents.

Figure S3: Inhibition of BCOADC activity by the anti-BCOADC-E1α-positive sera. The BCOADC activity was reconstituted in vitro by mixing purified E1, E2 and E3 components as described previously [24]. Before the assays, 1.25 εg of E1 was incubated with the indicated sera at a 200-fold dilution for 3 min on ice. The activities were calculated as percentages of the control activity without serum. Sera from two patients (P07 and P13) strongly inhibit the BCOADC activity, while normal sera (N01 and N02) do not.

Figure S4: Three-dimensional mapping of the epitope regions on the BCOADC-E1α subunit monomer. The epitope regions determined by ELISA were mapped on the crystal structure of the BCOADC-E1α subunit monomer (PDB: 2bev) [21]. The residue numbers of each region are shown. The antibody reactivities are indicated in red and pink, which correspond to +++ and ++ in Table 3, respectively.

Table S1: Numbers of patients with and without anti-PDC-E1α and anti-PDC-E2 antibodies. The appearance of anti-PDC-E1α antibodies was significantly linked to that of anti-PDC-E2 antibodies by Fisher's exact test (n = 30, P = 0.004).

Table S2: Core sequences of the epitopes defined by multipin ELISA. Synthesized peptides were tested for their reactivities with high-titer sera (P13 and P18). The amino acid sequences of the defined epitopes are represented by the single-letter code.

A list of the accession numbers for the BCOADC-E1α from various species. Amino acid sequences of these proteins were searched for homology with that of human BCOADC-E1α using the ClustalW2 program ( [28].

  1. Supplementary Material