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Mechanistic Shifts Along the Linear Free Energy Relationship for Aryl Phosphate Monoester Hydrolysis
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(English)Manuscript (preprint) (Other academic)
National Category
Theoretical Chemistry
URN: urn:nbn:se:uu:diva-278945OAI: oai:DiVA.org:uu-278945DiVA: diva2:907228
Available from: 2016-02-26 Created: 2016-02-26 Last updated: 2016-04-12
In thesis
1. Promiscuity and Selectivity in Phosphoryl Transferases
Open this publication in new window or tab >>Promiscuity and Selectivity in Phosphoryl Transferases
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Phosphoryl transfers are essential chemical reactions in key life processes, including energy production, signal transduction and protein synthesis. They are known for having extremely low reaction rates in aqueous solution, reaching the scale of millions of years. In order to make life possible, enzymes that catalyse phosphoryl transfer, phosphoryl transferases, have evolved to be tremendously proficient catalysts, increasing reaction rates to the millisecond timescale.

Due to the nature of the electronic structure of phosphorus atoms, understanding how hydrolysis of phosphate esters occurs is a complex task. Experimental studies on the hydrolysis of phosphate monoesters with acidic leaving groups suggest a concerted mechanism with a loose, metaphosphate-like transition state. Theoretical studies have suggested two possible concerted pathways, either with loose or tight transition state geometries, plus the possibility of a stepwise mechanism with the formation of a phosphorane intermediate. Different pathways were shown to be energetically preferable depending on the acidity of the leaving group. Here we performed computational studies to revisit how this mechanistic shift occurs along a series of aryl phosphate monoesters, suggesting possible factors leading to such change.

The fact that distinct pathways can occur in solution could mean that the same is possible for an enzyme active site. We performed simulations on the catalytic activity of β-phosphoglucomutase, suggesting that it is possible for two mechanisms to occur at the same time for the phosphoryl transfer.

Curiously, several phosphoryl transferases were shown to be able to catalyse not only phosphate ester hydrolysis, but also the cleavage of other compounds. We modeled the catalytic mechanism of two highly promiscuous members of the alkaline phosphatase superfamily. Our model reproduces key experimental observables and shows that these enzymes are electrostatically flexible, employing the same set of residues to enhance the rates of different reactions, with different electrostatic contributions per residue.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 74 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1350
phosphate chemistry, linear free energy relationships, phosphatase, catalytic promiscuity, empirical valence bond approach, alkaline phosphatase
National Category
Biochemistry and Molecular Biology
urn:nbn:se:uu:diva-279693 (URN)978-91-554-9497-1 (ISBN)
Public defence
2016-04-25, C8:305, BMC, Husarg. 3, Uppsala, 13:00 (English)
Available from: 2016-04-04 Created: 2016-03-03 Last updated: 2016-04-12

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