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From Proteopedia
X-ray structure of the H40A mutant of Ribonuclease T1 complexed with 3'-guanosine monophosphate
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedRibonucleases (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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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