Sandbox Reserved 1051: Difference between revisions
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[[Image:E228Q zoom.png |100 xp|left|thumb|'''Figure 9.''' [http://proteopedia.org/wiki/index.php/4qdz Ag85C-E228Q] active site. The glutamate residue is shifted four angstroms in the mutated form of this enzyme causing a rearrangement of hydrogen bonds within the enzyme. The histidine residue, labeled in pink, takes on two conformations, binding with alternative serine residues, labeled in red.]] | [[Image:E228Q zoom.png |100 xp|left|thumb|'''Figure 9.''' [http://proteopedia.org/wiki/index.php/4qdz Ag85C-E228Q] active site. The glutamate residue is shifted four angstroms in the mutated form of this enzyme causing a rearrangement of hydrogen bonds within the enzyme. The histidine residue, labeled in pink, takes on two conformations, binding with alternative serine residues, labeled in red.]] | ||
The mutation introduced in [http://proteopedia.org/wiki/index.php/4qdz Ag85C-E228Q] (Figure 8) causes the Glu228 of the catalytic triad to be shifted 4 angstroms from its original position in the native structure of Ag85C (Figure 9). Due to the shift of Glu228 is the loss of hydrogen bonds between Ser124 and His260. Instead, <scene name='69/694218/4qdz/ | The mutation introduced in [http://proteopedia.org/wiki/index.php/4qdz Ag85C-E228Q] (Figure 8) causes the Glu228 of the catalytic triad to be shifted 4 angstroms from its original position in the native structure of Ag85C (Figure 9). Due to the shift of Glu228 is the loss of hydrogen bonds between Ser124 and His260. Instead, <scene name='69/694218/4qdz/2'>His260 bonds with Ser148</scene>, which also results from the shift of Glu228. A weak electron density difference in the His260 position of the native and mutated structures was also noted, suggesting that the residue may take on two alternative conformations in the <scene name='69/694218/Ag85c-e228q/1'>Ag85C-E228Q</scene> mutant. Overall, the enzyme functionality is decreased to only 17% activity.<ref name="Favrot"/> | ||
Unlike other Ag85C mutants and modifications aforementioned, the <scene name='69/694218/Ag85c-e228q/1'>Ag85C-E228Q</scene>does not eliminate any hydrogen bonds in the catalytic triad. Rather, it simply replaces a carboxylate moiety with an amide. Further, the structural change observed in the low-energy conformation of the <scene name='69/694218/Ag85c-e228q/1'>Ag85C-E228Q</scene> mutant provides additional support for the hypothesis that the natively kinked helix α-9 is central to the enzymatic function of Ag85C.<ref name="Favrot"/> | Unlike other Ag85C mutants and modifications aforementioned, the <scene name='69/694218/Ag85c-e228q/1'>Ag85C-E228Q</scene>does not eliminate any hydrogen bonds in the catalytic triad. Rather, it simply replaces a carboxylate moiety with an amide. Further, the structural change observed in the low-energy conformation of the <scene name='69/694218/Ag85c-e228q/1'>Ag85C-E228Q</scene> mutant provides additional support for the hypothesis that the natively kinked helix α-9 is central to the enzymatic function of Ag85C.<ref name="Favrot"/> | ||
