1ajc
From Proteopedia
| Line 1: | Line 1: | ||
[[Image:1ajc.jpg|left|200px]] | [[Image:1ajc.jpg|left|200px]] | ||
| - | + | <!-- | |
| - | + | The line below this paragraph, containing "STRUCTURE_1ajc", creates the "Structure Box" on the page. | |
| - | + | You may change the PDB parameter (which sets the PDB file loaded into the applet) | |
| - | + | or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |
| - | + | or leave the SCENE parameter empty for the default display. | |
| - | | | + | --> |
| - | | | + | {{STRUCTURE_1ajc| PDB=1ajc | SCENE= }} |
| - | + | ||
| - | + | ||
| - | }} | + | |
'''THREE-DIMENSIONAL STRUCTURE OF THE D153G MUTANT OF E. COLI ALKALINE PHOSPHATASE: A MUTANT WITH WEAKER MAGNESIUM BINDING AND INCREASED CATALYTIC ACTIVITY''' | '''THREE-DIMENSIONAL STRUCTURE OF THE D153G MUTANT OF E. COLI ALKALINE PHOSPHATASE: A MUTANT WITH WEAKER MAGNESIUM BINDING AND INCREASED CATALYTIC ACTIVITY''' | ||
| Line 29: | Line 26: | ||
[[Category: Chen, L.]] | [[Category: Chen, L.]] | ||
[[Category: Dealwis, C G.]] | [[Category: Dealwis, C G.]] | ||
| - | [[Category: | + | [[Category: Non specific mono-esterase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 10:20:49 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 07:20, 2 May 2008
THREE-DIMENSIONAL STRUCTURE OF THE D153G MUTANT OF E. COLI ALKALINE PHOSPHATASE: A MUTANT WITH WEAKER MAGNESIUM BINDING AND INCREASED CATALYTIC ACTIVITY
Overview
The substitution of aspartate at position 153 in Escherichia coli alkaline phosphatase by glycine results in a mutant enzyme with 5-fold higher catalytic activity (kcat) but no change in Km at pH 8.0 in 50 mM Tris-HCl. The increased kcat is achieved by a faster release of the phosphate product as a result of the lower phosphate affinity. The mutation also affects Mg2+ binding, resulting in an enzyme with lower metal affinity. The 3-D X-ray structure of the D153G mutant has been refined at 2.5 A to a crystallographic R-factor of 16.2%. An analysis of this structure has revealed that the decreased phosphate affinity is caused by an apparent increase in flexibility of the guanidinium side chain of Arg166 involved in phosphate binding. The mutation of Asp153 to Gly also affects the position of the water ligands of Mg2+, and the loop Gln152-Thr155 is shifted by 0.3 A away from the active site. The weaker Mg2+ binding of the mutant compared with the wild type is caused by an altered coordination sphere in the proximity of the Mg2+ ion, and also by the loss of an electrostatic interaction (Mg2+.COO-Asp153) in the mutant. Its ligands W454 and W455 and hydroxyl of Thr155, involved in the octahedral coordination of the Mg2+ ion, are further apart in the mutant compared with the wild type.
About this Structure
1AJC is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
3-D structure of the D153G mutant of Escherichia coli alkaline phosphatase: an enzyme with weaker magnesium binding and increased catalytic activity., Dealwis CG, Chen L, Brennan C, Mandecki W, Abad-Zapatero C, Protein Eng. 1995 Sep;8(9):865-71. PMID:8746724 Page seeded by OCA on Fri May 2 10:20:49 2008
