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Figure 2 | Arthritis Research & Therapy

Figure 2

From: Effect of dsDNA binding to SmD-derived peptides on clinical accuracy in the diagnosis of systemic lupus erythematosus

Figure 2

Binding of SmD peptides to dsDNA. (a) SmD1, SmD3 and biotinylated control peptides (PM1-α and Ribosomal P) were serially diluted in dilution buffer (0.01–10 μg/ml) and incubated on dsDNA-coated ELISA plates. Unbound peptides were removed by washing. Immobilized peptides were detected by streptavidin–horseradish peroxidase conjugate in combination with 3,3',5,5'-tetramethylbenzidine substrate. The SmD1 peptide showed dsDNA binding starting with a concentration of approximately 40 ng/ml, and the SmD3 peptide starting with approximately 0.6 μg/ml. No dsDNA binding could be observed with PM1-α and Ribosomal P. (b) The inhibitory effect of the SmD1 and SmD3 peptides was analysed by testing an anti-dsDNA-positive sample from a systemic lupus erythematosus patient on dsDNA-coated microtitre strips preincubated with increasing concentrations of the SmD peptides as described above. Detection of bound human dsDNA antibodies was according to the instructions for use of the dsDNA ELISA (Dr Fooke Laboratories). No inhibition was observed for SmD3, but inhibition was observed for SmD1 starting at a concentration of approximately 1 μg/ml. OD, optical density.

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