Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1991-7-11
pubmed:abstractText
In order to examine the energetics in base-catalyzed hydrolysis of RNA, a tentative pentacoordinated intermediate (3) has been characterized by molecular orbital calculations. Ab initio studies at the level of 3-21G* indicate that, under the Cs symmetry restricted conditions, the P-O(2) bond possessing antiperiplanar (app) lone pair electrons (Ip) on the equatorial oxygen (O(3)) can be cleaved with almost no barrier (TS1 transition state; 0.08 kcal mol-1), from the pentacoordinated intermediate (3) of base-catalyzed hydrolysis of phosphate, compared to the P-O(5) bond (TS2 transition state; 28.9 kcal mol-1) which lacks app lp assistance from O(3). The dianionic intermediate, however, loses the TS1 transition state thus its property as an intermediate when the Cs restriction is removed. The analysis of the entire potential energy surface enables us to conclude that, in a related system examined by Lim and Karplus [1990) J. Am. Chem. Soc., 112, 5872-5873) for attack by OH- on ethylene phosphate monoanion, the TS1 transition state had also been lost and thus no intermediate had been found. These results further support our earlier conclusions (Taira et al. (1990) Protein Engineering, 3, 691-701) of rate limiting transition state possessing extended P-O(5') bond breaking character (the TS2 transition state) in the base-catalyzed hydrolysis of RNA. Finally, although the lack of 2',3' -migration of phosphate moieties in basic condition appears to be in accord with the short-lived intermediate, it really does not prove the absence of the intermediate. The detail will be discussed in the text.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0305-1048
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
19
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2747-53
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Rate limiting P-O(5') bond cleavage of RNA fragment: ab initio molecular orbital calculations on the base-catalyzed hydrolysis of phosphate.
pubmed:affiliation
Fermentation Research Institute, Agency of Industrial Science & Technology, Tsukuba Science City, Japan.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't