Thermal protection of E. coli cell extract by purified Mj HSP16.5. Cell extract (CE) from E. coli BL21(DE3)/pSJS1240 (2 mg/ml) was incubated with Mj HSP16.5 or cytochrome C at 2:1 or 1:1 (wt/wt) ratio at 80°C for 20 min. Samples were centrifuged, and the pellets were resuspended in the original volume. Ten microliters of each sample were run on a 15% SDS/PAGE gel. Lanes: 1, molecular mass markers in kilodaltons; 2, cell extract (CE), unheated (U); 3–4, CE, heated (H) 80°C, 20 min: insoluble pellet (I), supernatant (S); 5, CE:Mj HSP16.5 (2:1 wt/wt ratio), U; 6–7, CE:Mj HSP16.5 (2:1 wt/wt ratio), H 80°C, 20 min: I, S; 8, CE:Mj HSP16.5 (1:1 wt/wt ratio), U; 9–10, CE:Mj HSP16.5 (1:1 wt/wt ratio), H 80°C, 20 min: I, S; 11, CE:cytochrome C (1:1 wt/wt ratio), U; 12–13, CE:cytochrome C (1:1 wt/wt ratio), H 80°C, 20 min: I, S; 14, 1 μg Mj HSP16.5; 15, 5 μg cytochrome C.