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The structure of a thermally stable 3‐phosphoglycerate kinase and a comparison with its mesophilic equivalent
Author(s) -
Davies Gideon J.,
Gamblin Steven J.,
Littlechild Jennifer A.,
Watson Herman C.
Publication year - 1993
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340150306
Subject(s) - phosphoglycerate kinase , thermophile , mesophile , crystallography , differential scanning calorimetry , bacillus subtilis , chemistry , ionic bonding , helix (gastropod) , enzyme , thermal stability , thermodynamics , biochemistry , biology , organic chemistry , bacteria , ion , physics , ecology , snail , genetics
The structure of the phosphoglycerate kinase (PGK) from Bacillus stearothermophilus, a moderate thermophile, has been determined and compared with that of its mesophilic equivalent from yeast. The Bacillus enzyme structure was solved by molecular replacement and improved using constrained rigid‐body, molecular dynamics and conventional refinement procedures. The refinement residual, calculated using all the measured data between 8 and 1.65 Å, is 0.18(1). The stereo chemical deviations of the final model from ideality are 0.01 Å for both bonds and planes. The mid‐point temperatures of the Bacillus and yeast enzymes are 67 and 53°C, respectively. Differential scanning calorimetry indicates that the energy difference (ΔΔ G ) between the mesophilic and thermophilic enzymes is of the order of 5 kcal mol −1 at room temperature. The structure comparison indicates that the features most likely to be responsible for the increased thermal stability of the Bacillus enzyme are the increased internal hydrophobicity, additional ion pairs, and better α‐helix stability resulting from the removal of helix destablising residues and extra helix–dipole/helix side chain ionic interactions. © 1993 Wiley‐Liss, Inc.