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pK_a Values of Guanine in Water: Density Functional Theory Calculations Combined with Poisson−Boltzmann Continuum−Solvation Model

Jang, Yun Hee and Goddard, William A., III and Noyes, Katherine T. and Sowers, Lawrence C. and Hwang, Sungu and Chung, Doo Soo (2003) pK_a Values of Guanine in Water: Density Functional Theory Calculations Combined with Poisson−Boltzmann Continuum−Solvation Model. Journal of Physical Chemistry B, 107 (1). pp. 344-357. ISSN 1520-6106.

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It has long been postulated that rare tautomeric or ionized forms of DNA bases may play a role in mispair formation. To investigate the role this phenomenon plays in the mispairing of guanine and to develop a calculation methodology that can be extended to mutagenic DNA damage products, we used first principles quantum mechanics (density functional theory (B3LYP) with the Poisson−Boltzmann continuum−solvation model) to calculate the relative stabilities of tautomers of guanine in various environments and their pK_a values in aqueous solution. This method allows us to calculate site specific pK_a values — information that is experimentally inaccessible — as well as overall pK_a values for each stage, wherein our numbers are in agreement with experimental values. We find that neutral guanine exists in aqueous phase as a mixture of two major keto tautomers, the N_9H form (1) and a N_7H form (3). These keto forms are also major species present in the gas phase, as well as the O_6H enol tautomer (7a). These results show that tautomeric configurations can be drastically different depending on the environment. Here, we discuss the reasons for this environmental variability and suggest some possible implications. Finally, we estimate that the relative population of deprotonated guanine is 0.2−2% in the range of pH 7−8, a significant enough population to potentially play a role in mispair formation.

Item Type:Article
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URLURL TypeDescription
Jang, Yun Hee0000-0002-6604-5813
Goddard, William A., III0000-0003-0097-5716
Hwang, Sungu0000-0002-8722-9312
Chung, Doo Soo0000-0002-8335-3201
Additional Information:© 2003 American Chemical Society. Received 20 March 2002. Published online 5 December 2002. Published in print 1 January 2003. This work was supported in part by the National Institutes of Health [HD36385 (W.A.G.), GM 41336 (L.C.S.), and CA 85779 (L.C.S. and W.A.G.)] and the BK21 program and CMC of Korea (Y.H.J., S.H., and D.S.C.). In addition, the facilities of the MSC are also supported by DOE-ASCI, ARO-MURI, ARO-DURIP, National Science Foundation [CHE-99-85574 and 99-77872], Dow Chemical, 3M, Beckman Institute, Avery-Dennison, Chevron Corporation, Seiko Epson, Asahi Chemical, and Kellogg's.
Funding AgencyGrant Number
NIHCA 85779
Department of Energy (DOE)UNSPECIFIED
Army Research Office (ARO)UNSPECIFIED
Caltech Beckman InstituteUNSPECIFIED
Chevron CorporationUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20170519-142727313
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Official Citation:pKa Values of Guanine in Water:  Density Functional Theory Calculations Combined with Poisson−Boltzmann Continuum−Solvation Model Yun Hee Jang, William A. Goddard III, Katherine T. Noyes, Lawrence C. Sowers, Sungu Hwang, and Doo Soo Chung The Journal of Physical Chemistry B 2003 107 (1), 344-357 DOI: 10.1021/jp020774x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77608
Deposited By: Ruth Sustaita
Deposited On:22 May 2017 16:12
Last Modified:17 Nov 2020 00:14

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