FIG. 5.

The AKL PTS1 Peptide induces quaternary structural changes in LdPEX5. (A) Purified LdPEX5 (30 μg in 50 mM Tris [pH 8.0], 100 mM NaCl) was incubated in the absence (thin trace) or in the presence of a 40-fold molar (thick traces) excess of AKL peptide at 20°C for 1 h and then injected onto a sizing column composed of a tandemly plumbed Bio-Sil SEC 450-5/Bio-Sil SEC 250-5 (7.8 by 150 mm or 7.8 by 300 mm) equilibrated with 25 mM Tris-100 mM NaCl (pH 8.0)-2 mM DTT at a flow rate of 0.4 ml/min. Protein elution was monitored at 280 nm. (B) ldpex5 Δ269-291 in the absence (thin trace) or presence (thick trace) of an excess of AKL peptide incubated at 30°C for 3 h was analyzed on a Bio-Sil SEC 250-5 (7.8 by 600 mm) column by using a mobile phase of 25 mM Tris-100 mM NaCl (pH 8.0)-2 mM DTT at a flow rate of 0.25 ml/min. Quaternary structure of ldpex5 Δ269-291 in the presence of PTS1 was performed on the reaction mixture after the ITC analysis.