Fig. 1. Similarity of the overall fold (top) and local geometries (bottom) depending on sequence homology (in terms of sequence identity %) between the thermostable and mesophilic proteins. Each point represents a thermostable/mesophilic pair and numbered, with numbers encoding the following PDB ids: 1-1PCZ/1VOK, 2-1BDM/4MDH, 3-1BMD/1B8P, 4-1CAA/8RXN, 5-1CIU/1CDG, 6-1CYG/1CDG, 7-1EBD/1AOG, 8-1GTM/1HRD, 9-1HDG/1GAD, 10-1LDN/1LDG, 11-1LNF/1NPC, 12-1OBR/1AYE, 13-1QEZ/1OBW, 14-1Q9H/1GPI, 15-1THM/1BH6, 16-1TMY/3CHY, 17-1VJW/1FXD, 18-1WB8/1JA8, 19-1WL7/1UV4, 20-1XGS/1BN5, 21-1XYZ/1CLX, 22-1YNA/1XNB, 23-1YNA/1ENX, 24-1ZIP/1AKY, 25-2BMM/1NGK, 26-2PRD/1SXV, 27-3MDS/1D5N, 28-3TGL/1LGY, 29-4PFK/1PFK, 30-1YNR/451C.

Fig. 2. Numbers of water molecules scaled by water-accessible surfaces of protein subunits contained in a unit cell in crystals of thermophilic species protein versus mesophilic species proteins (light gray). (Top left) The representative dataset taken from [6]. (Top right) dataset verified by experimentally determined thermal stability of all proteins studied [24]. (Bottom) Dependence of scaled number of water molecules on crystallographic resolution.

Fig. 3. Numbers of internal water molecules per 10 kDa molecular weight of protein in crystals of thermophilic (dark gray) versus mesophilic proteins (light gray).

Fig. 4. Desorbed water versus temperature for non-oriented self-assembled film of E. coli TrxEc (black squares), BacTrx in non-oriented self-assembled (white squares) and LB (gray squares) film. The water amount has been normalized to the initial protein amount in the sample. Thioredoxin samples were deposited on the quartz crystals in 50 mM sodium phosphate pH 5.8 and dried under vacuum for 30 min [19] and [34].

Fig. 5. Temperature dependence of circular dichroism signal at 193 nm LB film (black line) and in non-oriented self-assembled film of BacTrx (light gray line). Measurements have been taken in 50 mM sodium phosphate pH 5.8. The CD signal for non-oriented self-assembled film of E. coli EcTrx displays a melting temperature about 13 °C lower than the corresponding BacTrx one (dark gray line). Instead, the LB film of E. coli EcTrx even after heating up to 200 °C does not display a melting transition (black line). The CD signal has been normalized to the initial molar ellipticity value of the BacTrx self-assembled film sample at 25 °C.

Fig. 6. Positions of internal and first hydration shell water (red) around the B. acidocaldarius thioredoxin (top) and the E. coli thioredoxin (bottom). Left and right panels differ by 180° rotation around a horizontal y-axis. Hydrophilic surface is in green, hydrophobic surface is in white. (For interpretation of color mentioned in this figure the reader is referred to the web version of the article.)

Numbers of water molecules per subunit in crystals of several thioredoxins