1low: Difference between revisions

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

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

caption="1low, resolution 1.9Å" />

'''X-ray structure of the H40A mutant of Ribonuclease T1 complexed with 3'-guanosine monophosphate'''<br />

==Overview==

Ribonucleases (RNases) catalyze the cleavage of the phosphodiester bond in, RNA up to 10(15)-fold, as compared with the uncatalyzed reaction. High, resolution crystal structures of these enzymes in complex with, 3'-mononucleotide substrates demonstrate the accommodation of the, nucleophilic 2'-OH group in a binding pocket comprising the catalytic base, (glutamate or histidine) and a charged hydrogen bond donor (lysine or, histidine). Ab initio quantum chemical calculations performed on such, Michaelis complexes of the mammalian RNase A (EC ) and the microbial RNase, T(1) (EC ) show negative charge build up on the 2'-oxygen upon substrate, binding. The increased nucleophilicity results from stronger hydrogen, bonding to the catalytic base, which is mediated by a hydrogen bond from, the charged donor. This hitherto unrecognized catalytic dyad in, ribonucleases constitutes a general mechanism for nucleophile activation, in both enzymic and RNA-catalyzed phosphoryl transfer reactions.

Ribonucleases (RNases) catalyze the cleavage of the phosphodiester bond in RNA up to 10(15)-fold, as compared with the uncatalyzed reaction. High resolution crystal structures of these enzymes in complex with 3'-mononucleotide substrates demonstrate the accommodation of the nucleophilic 2'-OH group in a binding pocket comprising the catalytic base (glutamate or histidine) and a charged hydrogen bond donor (lysine or histidine). Ab initio quantum chemical calculations performed on such Michaelis complexes of the mammalian RNase A (EC ) and the microbial RNase T(1) (EC ) show negative charge build up on the 2'-oxygen upon substrate binding. The increased nucleophilicity results from stronger hydrogen bonding to the catalytic base, which is mediated by a hydrogen bond from the charged donor. This hitherto unrecognized catalytic dyad in ribonucleases constitutes a general mechanism for nucleophile activation in both enzymic and RNA-catalyzed phosphoryl transfer reactions.

==About this Structure==

1LOW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_oryzae Aspergillus oryzae] with CA and 3GP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonuclease_T(1) Ribonuclease T(1)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.3 3.1.27.3] Full crystallographic information is available from [http://~~ispc~~.weizmann.ac.il/oca-bin/ocashort?id=1LOW OCA].

1LOW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_oryzae Aspergillus oryzae] with <scene name='pdbligand=CA:'>CA</scene> and <scene name='pdbligand=3GP:'>3GP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonuclease_T(1) Ribonuclease T(1)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.3 3.1.27.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LOW OCA].

==Reference==

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[[Category: rnase]]

''Page seeded by [http://~~ispc~~.weizmann.ac.il/oca OCA ] on ~~Tue Nov 20 20~~:44:~~21 2007~~''

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:46:59 2008''

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@@ Line 1: / Line 1: @@
-[[Image:1low.gif|left|200px]]<br /><applet load="1low" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1low.gif|left|200px]]<br /><applet load="1low" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1low, resolution 1.9&Aring;" />
 '''X-ray structure of the H40A mutant of Ribonuclease T1 complexed with 3'-guanosine monophosphate'''<br />
 ==Overview==
-Ribonucleases (RNases) catalyze the cleavage of the phosphodiester bond in, RNA up to 10(15)-fold, as compared with the uncatalyzed reaction. High, resolution crystal structures of these enzymes in complex with, 3'-mononucleotide substrates demonstrate the accommodation of the, nucleophilic 2'-OH group in a binding pocket comprising the catalytic base, (glutamate or histidine) and a charged hydrogen bond donor (lysine or, histidine). Ab initio quantum chemical calculations performed on such, Michaelis complexes of the mammalian RNase A (EC ) and the microbial RNase, T(1) (EC ) show negative charge build up on the 2'-oxygen upon substrate, binding. The increased nucleophilicity results from stronger hydrogen, bonding to the catalytic base, which is mediated by a hydrogen bond from, the charged donor. This hitherto unrecognized catalytic dyad in, ribonucleases constitutes a general mechanism for nucleophile activation, in both enzymic and RNA-catalyzed phosphoryl transfer reactions.
+Ribonucleases (RNases) catalyze the cleavage of the phosphodiester bond in RNA up to 10(15)-fold, as compared with the uncatalyzed reaction. High resolution crystal structures of these enzymes in complex with 3'-mononucleotide substrates demonstrate the accommodation of the nucleophilic 2'-OH group in a binding pocket comprising the catalytic base (glutamate or histidine) and a charged hydrogen bond donor (lysine or histidine). Ab initio quantum chemical calculations performed on such Michaelis complexes of the mammalian RNase A (EC ) and the microbial RNase T(1) (EC ) show negative charge build up on the 2'-oxygen upon substrate binding. The increased nucleophilicity results from stronger hydrogen bonding to the catalytic base, which is mediated by a hydrogen bond from the charged donor. This hitherto unrecognized catalytic dyad in ribonucleases constitutes a general mechanism for nucleophile activation in both enzymic and RNA-catalyzed phosphoryl transfer reactions.
 ==About this Structure==
-LOW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_oryzae Aspergillus oryzae] with CA and 3GP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonuclease_T(1) Ribonuclease T(1)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.3 3.1.27.3] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1LOW OCA].
+LOW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_oryzae Aspergillus oryzae] with <scene name='pdbligand=CA:'>CA</scene> and <scene name='pdbligand=3GP:'>3GP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ribonuclease_T(1) Ribonuclease T(1)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.3 3.1.27.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LOW OCA].
 ==Reference==
@@ Line 26: / Line 26: @@
 [[Category: rnase]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 20:44:21 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:46:59 2008''