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Figure 3 | BMC Biochemistry

Figure 3

From: High affinity binding of hydrophobic and autoantigenic regions of proinsulin to the 70 kDa chaperone DnaK

Figure 3

Quantitative analysis of proinsulin peptide binding to DnaK. A: For DnaK-binding peptides of the proinsulin A-, B-chain or C- peptide the amount of DnaK released during the three electroelution cycles was determined in order to assess the progress of DnaK dissociation from the peptides. For this analysis the strength of the signals obtained from the high affinity DnaK ligand C3 after each elution cycle (cycle 1: 134 LU; cycle 2: 46 LU; cycle 3: 33 LU) was set as "1" and used as reference for the signal strengths obtained from the investigated peptides after the corresponding cycles of elution. For each peptide, the resulting three data points (corresponding to the three elution cycles) were subjected to linear regression analysis and for better comparison of the progress of dissociation a line was plotted against the elution cycles. The bold line in the left panel indicates the release of the B-chain peptide 18. In a fluid phase competition assay a-NR (200 nM) and DnaK (1 μM) were incubated in the presence of increasing concentrations of peptide B11-23 (solid circles) or B18-30 (open circles) (B) or increasing concentrations of proinsulin (solid circles) or insulin (open circles) (C). The difference in fluorescence emission intensity at 500 nm was plotted as a function of the concentrations of peptides or proteins.

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