5JB7
A simplified BPTI variant containing 24 alanines out of 58 residues
Summary for 5JB7
| Entry DOI | 10.2210/pdb5jb7/pdb |
| Related | 5JB4 5JB5 5JB6 |
| Descriptor | Pancreatic trypsin inhibitor, SULFATE ION (3 entities in total) |
| Functional Keywords | bovine pancreatic trypsin inhibitor variant, sequence simplification, 24 alanines, protein design, hydrolase inhibitor |
| Biological source | Bos taurus (Bovine) |
| Total number of polymer chains | 3 |
| Total formula weight | 17539.64 |
| Authors | Islam, M.M. (deposition date: 2016-04-13, release date: 2017-04-19, Last modification date: 2024-11-06) |
| Primary citation | Islam, M.M.,Yohda, M.,Kidokoro, S.,Kuroda, Y. Crystal structures of highly simplified BPTIs provide insights into hydration-driven increase of unfolding enthalpy Sci Rep, 7:41205-41205, 2017 Cited by PubMed Abstract: We report a thermodynamic and structural analysis of six extensively simplified bovine pancreatic trypsin inhibitor (BPTI) variants containing 19-24 alanines out of 58 residues. Differential scanning calorimetry indicated a two-state thermal unfolding, typical of a native protein with densely packed interior. Surprisingly, increasing the number of alanines induced enthalpy stabilization, which was however over-compensated by entropy destabilization. X-ray crystallography indicated that the alanine substitutions caused the recruitment of novel water molecules facilitating the formation of protein-water hydrogen bonds and improving the hydration shells around the alanine's methyl groups, both of which presumably contributed to enthalpy stabilization. There was a strong correlation between the number of water molecules and the thermodynamic parameters. Overall, our results demonstrate that, in contrast to our initial expectation, a protein sequence in which over 40% of the residues are alanines can retain a densely packed structure and undergo thermal denaturation with a large enthalpy change, mainly contributed by hydration. PubMed: 28266637DOI: 10.1038/srep41205 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.9 Å) |
Structure validation
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