1loy
From Proteopedia
|
X-ray structure of the H40A/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
1LOY 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
Page seeded by OCA on Tue Nov 20 20:44:25 2007
