1lov: Difference between revisions
New page: left|200px<br /><applet load="1lov" size="450" color="white" frame="true" align="right" spinBox="true" caption="1lov, resolution 1.55Å" /> '''X-ray structure of t... |
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[[Image:1lov.gif|left|200px]]<br /><applet load="1lov" size=" | [[Image:1lov.gif|left|200px]]<br /><applet load="1lov" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1lov, resolution 1.55Å" /> | caption="1lov, resolution 1.55Å" /> | ||
'''X-ray structure of the E58A mutant of Ribonuclease T1 complexed with 3'-guanosine monophosphate'''<br /> | '''X-ray structure of the E58A mutant of Ribonuclease T1 complexed with 3'-guanosine monophosphate'''<br /> | ||
==Overview== | ==Overview== | ||
Ribonucleases (RNases) catalyze the cleavage of the phosphodiester bond in | 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== | ==About this Structure== | ||
1LOV 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:// | 1LOV 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=1LOV OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: rnase]] | [[Category: rnase]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:46:59 2008'' | ||
Revision as of 11:47, 21 February 2008
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X-ray structure of the E58A mutant of Ribonuclease T1 complexed with 3'-guanosine monophosphate
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.
About this Structure
1LOV is a Single protein structure of sequence from Aspergillus oryzae with CA and 3GP as ligands. Active as Ribonuclease T(1), with EC number 3.1.27.3 Full crystallographic information is available from OCA.
Reference
A nucleophile activation dyad in ribonucleases. A combined X-ray crystallographic/ab initio quantum chemical study., Mignon P, Steyaert J, Loris R, Geerlings P, Loverix S, J Biol Chem. 2002 Sep 27;277(39):36770-4. Epub 2002 Jul 16. PMID:12122018
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