Charles Iden, PhD (Professor Emeritus)

Professor Emeritus


Ph.D., The Johns Hopkins University

Postdoctoral, Brookhaven National Laboratory

Investigations of DNA Damage Produced by Genotoxic Substances

The focus of research in this laboratory is to examine damage to DNA caused by carcinogenic and mutagenic compounds and to identify DNA adducts or cross-links by modern analytical methods. Genotoxic chemicals vary greatly in their structure and reactivity, and the chemical nature of DNA adducts and other lesions that leads to a specific mutation has not been clearly established for many of these substances. Nucleotides and nucleosides have been used as targets for these studies, and while reactions at the monomeric level are useful, the substantive question is whether these adducts are formed in DNA in biological systems. Thus, investigation of reactions of genotoxic chemicals with native DNA is essential. Small amounts of adducts formed under physiological conditions and unstable adducts require state-of-the-art analytical methods to identify the full spectrum of products. High-performance liquid chromatography, capillary zone electrophoresis, nuclear magnetic resonance, and a variety of mass spectrometer techniques including ESI/MS and LC/MS/MS are used to characterize DNA adducts. In addition, it is also important to characterize the physical properties of DNA containing these lesions and to examine the processing of lesions by selected enzyme systems. Consequently, the preparation of site-specifically modified oligodeoxynucleotides is a second area of interest. Small DNA molecules can be constructed with any base sequence and may incorporate one or more modified nucleotides; they are synthesized on an Applied Biosystems Automated DNA Synthesizer. Modified oligomers are purified by HPLC techniques and used in a variety of biological or physical research programs.



Rieger, R. A.; McTigue, M. M.; Kycia, J. H.; Gerchman, S. E.; Grollman, A. P.; Iden, C. R. Characterization of a Cross-linked DNA-Endo VIII Repair Complex by Electrospray Ionization Mass Spectrometry, J. Amer. Soc. Mass Spectrom., 2000, 11, 505-515.

Ferguson, P. L.; Iden, C. R.; Brownawell, B. J. Analysis of Alkylphenol Ethoxylate Metabolites in the Aquatic Environment Using Electrospray Liquid Chromatography Mass Spectrometry, Anal. Chem., 2000, 72, 4322-4330.

Ferguson, P. L.; Iden, C. R.; Brownawell, B. J. Distribution and Fate of Neutral Alkylphenol Ethoxylate Metabolites in a Sewage-Impacted Urban Estuary, Environ. Sci. Technol., 2001, 35, 2428-2435.

Rieger, R. A.; Iden, C. R. Characterization of the Stereoisomers of Thymidine Glycol in Synthetic Oligodeoxynucleotides, in Advances in Mass Spectrometry; Gelpi, E., Ed., John Wiley and Sons, Chichester, 2001; Vol. 15, pp 613-614.

Ferguson, P. L.; Iden, C. R.; McElroy, A. E.; Brownawell, B. J. Determination of Steroid Estrogens in Wastewater by Immunoaffinity Extraction Coupled with HPLC-Electrospray-MS, Anal. Chem., 2001, 73, 3890-3895.

Ferguson, P. L.; Iden, C. R.; Brownawell, B. J. Analysis of Nonylphenol and Nonylphenol Ethoxylates in Environmental Samples by Mixed-mode High Performance Liquid Chromatography-Electrospray Mass Spectrometry, J. Chromatogr. A., 2001, 938, 79-91.

Li, H.; Lewis, A.; Brodsky, S.; Rieger, R.; Iden, C. R.; Goligorsky, M. S. Homocysteine Induces 3-Hydroxy-3-3methylglutaryl Coenzyme A Reductase in Vascular Endothelial Cells: A Methanism for Development of Atherosclerosis, Circulation, 2002, 105, 1037-1043.

Johnson, F.; Bonala, R.; Tawdry, D.; Torres, M. C.; Iden, C. R. Efficient Synthesis of the Benzo(a)pyrene Metabolic Adducts of 2'-Deoxyguanosine and 2'-Deoxyadenosine and Their Direct Incorporation into DNA, Chem. Res. Toxicol., 2002,15, 1489-1494.

Huang, Y.; Torres, M. C.;Iden, C. R.; Johnson, F. Synthesis of the Minor Acrolein Adducts of 2'-Deoxyguanosine and Their Generation in Oligomeric DNA, Bioorganic Chem. 2003, in press.

Benotti, M. J.; Ferguson, P. L.; Rieger, R. A.; Iden, C. R.; Heine, C. E.; Brownawell, B. J. HPLC time-of-flight mass spectrometry: An alternative to LC-MS/MS for sensitive and selective determination of polar organic contaminants in the aquatic environment, ACS Symposium Series, 2003, in press.

Huang, Y.; Torres, M. C.; Iden, C. R.; Johnson, F. Regioselective Synthesis of 1, N2-Etheno-2'-Deoxyguanosine and its Generation in Oligomeric DNA, Chem. Res. Toxicol., 2003, in press.

Miller, H.; Fernandes, A. S.; Zaika, E.; McTigue, M. M.; Torres, M. C.; Wente, M.; Iden, C. R.; Grollman, A. P. Stereoselective Excision of Thymine Glycol from Oxidatively Damaged DNA, Nucl. Acids Res., 2004, 32, 338-345.

McTigue, M. M.; Rieger, R. A.; Rosenquist, T. A.; Iden, C. R.; de los Santos, C. R. Stereoselective Excision of Thymine Glycol Lesions by Mammalian Cell Extracts, DNA Repair, 2004, 3, 313-322.

Parathath, S.; Rieger, R. A.; Connelly, M. A.; Klein, S. M.; Abumrad, M. de la L.-M.; Iden, C. R.; Rothblat, G. H.; Williams, D. L. Changes in Plasma Membrane Properties and Phosphatidylcholine Subspecies of Insect Sf9 Cells Due to Expression of Class B Scavenger Receptors SR-B1 and CD36, J. Biol. Chem., 2004, 279, 41310-41318.

Bonala, R.; Torres, M. C.; Attaluri, S.; Iden, C. R.; Johnson, F. The Incorporation of the N2-Deoxyguanosine Metabolic Adducts of 2-Aminonaphthalene and 2-Aminofluorene into Oliomeric DNA, Chem. Res. Toxicol., 2005, 18, 457-465.

Reddy, S.; Iden, C. R.; Brownawell, B. J. Analysis of steroid conjugates in sewage influent and effluent by liquid chromatography-tandem mass spectrometry, Anal. Chem., 2005,77, 7032-7038.

Rieger, R. A.; Zaika, E. I.; Xie, W.; Johnson, F.; Grollman, A. P.; Iden, C. R.; Zharkov, D. O. Proteomic Approach to Identification of Proteins Reactive for Abasic Sites in DNA, Mol. Cell Proteomics, 2006, 5, 858-867.

Bonala, R.; Torres, M. C.; Iden, C. R.; Johnson, F. Synthesis of the PhIP Adduct of 2'-Deoxyguanosine and its Incorporation into Oligomeric DNA, Chem. Res. Toxicol., 2006, 19, 734-738.

Attaluri, S.; Bonala, R.R.; Yang, I.-Y.; Lukin, M.A.,;Wen, Y.; Grollman, A.P.; Moriya, M., Iden, C.R.; Johnson, F.  DNA Adducts of Aristolochic Acid-II:  Total Synthesis and Site-specific Mutagenesis Studies in Mammalian Cells, Nucl. Acids Res. 2010, 38, 339-352.

Minetti, C.A.; Remeta, D.P.; Johnson, F.; Iden, C.R.; Breslauer, K.J. Impact of alpha-Hydroxy-Propanodeoxyguanine adducts on DNA duplex energetics: Opposite base modulation and implications for mutagenicity and genotoxicity. Biopolymers. 2010, 93, 370-382.