1djo: Difference between revisions

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[[Image:1djo.gif|left|200px]]<br /><applet load="1djo" size="~~450~~" color="white" frame="true" align="right" spinBox="true"

[[Image:1djo.gif|left|200px]]<br /><applet load="1djo" size="350" color="white" frame="true" align="right" spinBox="true"

caption="1djo, resolution 2.00Å" />

'''CRYSTAL STRUCTURE OF PSEUDOMONAS 7A GLUTAMINASE-ASPARAGINASE WITH THE INHIBITOR DONV COVALENTLY BOUND IN THE ACTIVE SITE'''<br />

==Overview==

Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of, D and L isomers of glutamine and asparagine. Crystals of PGA were reacted, with diazo analogues of glutamine (6-diazo-5-oxo-L-norleucine, DON) and, asparagine (5-diazo-4-oxo-L-norvaline, DONV), which are known inhibitors, of the enzyme. The derivatized crystals remained isomorphous to native PGA, crystals. Their structures were refined to crystallographic R = 0.20 and, R(free) = 0.24 for PGA-DON and R = 0.19 and R = 0.23 for PGA-DONV., Difference Fourier electron density maps clearly showed that both DON and, DONV inactivate PGA through covalent inhibition. Continuous electron, density connecting the inhibitor to both Thr20 and Tyr34 of the flexible, loop was observed providing strong evidence that Thr20 is the primary, catalytic nucleophile and that Tyr34 plays an important role in catalysis, as well. The unexpected covalent binding observed in the PGA-DON and, PGA-DONV complexes shows that a secondary reaction involving the formation, of a Tyr34-inhibitor bond takes place with concomitant inactivation of, PGA. The predicted covalent linkage is not seen, however, suggesting an, alternative method of inhibition not yet seen for these diazo analogues., These surprising results give insight as to the role of the flexible loop, Thr and Tyr in the catalytic mechanism.

Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of D and L isomers of glutamine and asparagine. Crystals of PGA were reacted with diazo analogues of glutamine (6-diazo-5-oxo-L-norleucine, DON) and asparagine (5-diazo-4-oxo-L-norvaline, DONV), which are known inhibitors of the enzyme. The derivatized crystals remained isomorphous to native PGA crystals. Their structures were refined to crystallographic R = 0.20 and R(free) = 0.24 for PGA-DON and R = 0.19 and R = 0.23 for PGA-DONV. Difference Fourier electron density maps clearly showed that both DON and DONV inactivate PGA through covalent inhibition. Continuous electron density connecting the inhibitor to both Thr20 and Tyr34 of the flexible loop was observed providing strong evidence that Thr20 is the primary catalytic nucleophile and that Tyr34 plays an important role in catalysis as well. The unexpected covalent binding observed in the PGA-DON and PGA-DONV complexes shows that a secondary reaction involving the formation of a Tyr34-inhibitor bond takes place with concomitant inactivation of PGA. The predicted covalent linkage is not seen, however, suggesting an alternative method of inhibition not yet seen for these diazo analogues. These surprising results give insight as to the role of the flexible loop Thr and Tyr in the catalytic mechanism.

==About this Structure==

1DJO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_sp. Pseudomonas sp.] with CAB as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutamin-(asparagin-)ase Glutamin-(asparagin-)ase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.1.38 3.5.1.38] Full crystallographic information is available from [http://~~ispc~~.weizmann.ac.il/oca-bin/ocashort?id=1DJO OCA].

1DJO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_sp. Pseudomonas sp.] with <scene name='pdbligand=CAB:'>CAB</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutamin-(asparagin-)ase Glutamin-(asparagin-)ase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.1.38 3.5.1.38] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DJO OCA].

==Reference==

Line 14:

[[Category: Pseudomonas sp.]]

[[Category: Single protein]]

[[Category: Lacount, M.W.]]

[[Category: Lacount, M W.]]

[[Category: Lebioda, L.]]

[[Category: Lewinski, K.]]

Line 28:

[[Category: suicide inhibitor]]

''Page seeded by [http://~~ispc~~.weizmann.ac.il/oca OCA ] on ~~Tue Nov 20 13~~:20:~~14 2007~~''

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:17:13 2008''

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@@ Line 1: / Line 1: @@
-[[Image:1djo.gif|left|200px]]<br /><applet load="1djo" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1djo.gif|left|200px]]<br /><applet load="1djo" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1djo, resolution 2.00&Aring;" />
 '''CRYSTAL STRUCTURE OF PSEUDOMONAS 7A GLUTAMINASE-ASPARAGINASE WITH THE INHIBITOR DONV COVALENTLY BOUND IN THE ACTIVE SITE'''<br />
 ==Overview==
-Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of, D and L isomers of glutamine and asparagine. Crystals of PGA were reacted, with diazo analogues of glutamine (6-diazo-5-oxo-L-norleucine, DON) and, asparagine (5-diazo-4-oxo-L-norvaline, DONV), which are known inhibitors, of the enzyme. The derivatized crystals remained isomorphous to native PGA, crystals. Their structures were refined to crystallographic R = 0.20 and, R(free) = 0.24 for PGA-DON and R = 0.19 and R = 0.23 for PGA-DONV., Difference Fourier electron density maps clearly showed that both DON and, DONV inactivate PGA through covalent inhibition. Continuous electron, density connecting the inhibitor to both Thr20 and Tyr34 of the flexible, loop was observed providing strong evidence that Thr20 is the primary, catalytic nucleophile and that Tyr34 plays an important role in catalysis, as well. The unexpected covalent binding observed in the PGA-DON and, PGA-DONV complexes shows that a secondary reaction involving the formation, of a Tyr34-inhibitor bond takes place with concomitant inactivation of, PGA. The predicted covalent linkage is not seen, however, suggesting an, alternative method of inhibition not yet seen for these diazo analogues., These surprising results give insight as to the role of the flexible loop, Thr and Tyr in the catalytic mechanism.
+Pseudomonas 7A glutaminase-asparaginase (PGA) catalyzes the hydrolysis of D and L isomers of glutamine and asparagine. Crystals of PGA were reacted with diazo analogues of glutamine (6-diazo-5-oxo-L-norleucine, DON) and asparagine (5-diazo-4-oxo-L-norvaline, DONV), which are known inhibitors of the enzyme. The derivatized crystals remained isomorphous to native PGA crystals. Their structures were refined to crystallographic R = 0.20 and R(free) = 0.24 for PGA-DON and R = 0.19 and R = 0.23 for PGA-DONV. Difference Fourier electron density maps clearly showed that both DON and DONV inactivate PGA through covalent inhibition. Continuous electron density connecting the inhibitor to both Thr20 and Tyr34 of the flexible loop was observed providing strong evidence that Thr20 is the primary catalytic nucleophile and that Tyr34 plays an important role in catalysis as well. The unexpected covalent binding observed in the PGA-DON and PGA-DONV complexes shows that a secondary reaction involving the formation of a Tyr34-inhibitor bond takes place with concomitant inactivation of PGA. The predicted covalent linkage is not seen, however, suggesting an alternative method of inhibition not yet seen for these diazo analogues. These surprising results give insight as to the role of the flexible loop Thr and Tyr in the catalytic mechanism.
 ==About this Structure==
-DJO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_sp. Pseudomonas sp.] with CAB as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutamin-(asparagin-)ase Glutamin-(asparagin-)ase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.1.38 3.5.1.38] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1DJO OCA].
+DJO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_sp. Pseudomonas sp.] with <scene name='pdbligand=CAB:'>CAB</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutamin-(asparagin-)ase Glutamin-(asparagin-)ase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.1.38 3.5.1.38] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DJO OCA].
 ==Reference==
@@ Line 14: / Line 14: @@
 [[Category: Pseudomonas sp.]]
 [[Category: Single protein]]
-[[Category: Lacount, M.W.]]
+[[Category: Lacount, M W.]]
 [[Category: Lebioda, L.]]
 [[Category: Lewinski, K.]]
@@ Line 28: / Line 28: @@
 [[Category: suicide inhibitor]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 13:20:14 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:17:13 2008''