Education

Degree	Institution	Major
BA	Brooklyn College	Chemistry
PhD	State University of New York, Upstate Medical Center	Biochemistry

Post-Graduate Training

Training	Institution	Specialty
Postdoctoral	Johnson Research Foundation, University of Pennsylvania	a) Studies on mechanism of action of cytochrome P450 monooxygenases b) Role of orthologous cytochromes P450 in tissue development c) Development of screens for identification of tissue-selective carcinogen identification.

Awards

Name of Award/Honor	Awarding Organization
Travel Awardee to Britain	Wellcome Research
Awardee	Japan Society for Promotion of Science
Travel Awardee to Britain	Wellcome Research
Travel Awardee to Britain	Wellcome Research
Career Development Awardee	National Institutes of Health
Career Development Awardee	National Institutes of Health
Career Development Awardee	National Institutes of Health
Career Development Awardee	National Institutes of Health
Career Development Awardee	National Institutes of Health
Career Development Awardee	National Institutes of Health
Visiting Scientist Awardee to Japan	National Science Foundation

Name & Description	Category	Role	Type	Scope	Start Year	End Year
American Society for Pharmacology and Experimental Therapeutics: Member Drug Metabolism Division	Professional/Scientific Organization	Elected Counselor	External	National	1995	1998
Association of Medical School Pharmacologists	Professional/Scientific Organization	Councilor	External	National	1987	1989
British Biochemical Society	Professional/Scientific Organization	Member	External	International	1971
American Society for Biochemistry and Molecular Biology	Professional/Scientific Organization	Member	External	National	1971
American Society for Pharmacology and Experimental Therapeutics	Professional/Scientific Organization	Member	External	National	1969

The cytochrome P450s are ubiquitous proteins found in most phyla. Several thousand different forms have already been identified. The individual species have large numbers of cytochrome P450 forms. In humans, for example, 57 different forms of cytochrome P450 have been identified in the genome. The mouse genome contains 93 different forms. The different forms of cytochrome P450 can be grouped into families, based upon amino acid sequence identity. In mammals, families 1-3 are generally considered as 'xenobiotic-metabolizing' enzymes, oxidizing the greatest number of drugs and chemicals encountered in the environment, as well as a number of endobiotics like steroids destined for excretion or used in intermediary metabolism of compounds necessary for homeostasis. Most of the families of cytochrome P450 are involved, in one way or another, in steroidogenesis, vitamin metabolism or maintenance of homeostasis in the body. In recent studies, however, it has become apparent that a number of the xenobiotic metabolizing cytochrome P450s are present in the conceptus and the developing embryo and fetus at specific times after conception (Choudhary et al., 2004a; Choudhary et al., 2003; Choudhary et al., 2005), appearing to function as development-influencing gene products (Schenkman et al., 2003).

Mutations in the cytochrome P450 1B1 (CYP1B1) gene in humans results in the disease, Primary Congenital Glaucoma (PCG), which appears to be due to abnormal development of the trabecular meshwork at the angle of the eye. Although the mouse does not develop the same disease phenotype, damage to the mouse orthologous gene does result in similar histologically observed abnormal development of the trabecular meshwork. We have shown that point mutations in the human gene, which in patients cause PCG, result in forms of CYP1B1 that are expressed as a holoenzyme, with lesser stability and lower specific activity toward endobiotics (Choudhary et al., 2004b; Jansson et al., 2001). We have used the mouse to examine the temporal and spatial appearance of Cyp1b1 (the mouse ortholog) protein in mouse eye structures by histological and immunohistological methods (Choudhary et al., 2006) in order to gain an understanding of how the absence of a fully active form of the enzyme might result in the PCG phenotype. We note that, "the distinctive constitutive expression pattern of some CYPs during mouse ontogeny and their presence in human fetal tissues suggests an involvement in morphogenesis and patterning of different embryonic structures. This might occur by modulating the level of ligands required for activation of membrane or nuclear receptors", and it was suggested that such ligands were probably endobiotics of lipophilic properties (Choudhary et al., 2006). Examination of the effects of four different PCG-causing mutations of CYP1B1 on the stability and catalytic activities revealed impairment of these characteristics by the mutations, strongly suggestion diminution of function in the absence of enhanced levels of the enzyme are the cause of the observed PCG phenotype (Choudhary et al., 2008). Toward this observation, it was suggested that CYP1B1 might eventually serve as a potential target for gene therapy of the PCG condition (Choudhary et al., 2009).

Metabolism of different chemicals by cytochrome P450 forms often results in their conversion into active electrophiles that can react with DNA. It is generally accepted that such reactions are the cause of different cancers. In other studies we have been examining the ability to make use of cytochrome P450 forms in electrochemical analysis of the potential of different drugs and environmental pollutants to cause genotoxic effects by virtue of reacting with the DNA in thin films (Estavillo et al., 2003; Munge et al., 2003; Rusling et al., 2008; Zhou et al., 2003). Using microsomes containing cytochrome P450 and cytochrome P450 reductase (CPR) we have been able to show the involvement of CPR in the electrochemical activation of these environmental pollutants by cytochrome P450 forms (Sultana et al., 2005; Sultana et al., 2007). In attempts to make rapid throughput of analyses, arrays have been developed in which multiple forms of activating enzyme could be inserted to take advantage of differences in substrate specificities (Wang et al., 2005). Using the electrochemical method and layer-by-layer formation of interacting cytochrome P450 system components and DNA it could be shown that reactive intermediates were formed which could complex with and damage the DNA (Krishnan et al., 2007; So et al., 2008; So et al., 2007). Arrays for the electrochemical activation of the carcinogen benzo(a)pyrene by multiple forms of cytochrome P450 were developed (Hvastkovs et al., 2007). One could also use microsomes containing mixtures of metabolic enzymes in thin films with DNA for screening compounds for genotoxicity (Krishnan et al., 2008), or pure enzymes, developing methods for screening the DNA (Bajrami et al., 2008; Fundador et al., 2008). We have been monitoring DNA reactivity with different potential toxicants (Bajrami et al., 2009; Hull et al., 2009; Krishnan et al., 2009; Zhao et al., 2009a; Zhao et al., 2009b).

Not accepting students for Lab Rotations at this time

Journal Articles

Books

Book Chapters

Abstracts

Conference Papers

Newsletters

Other

Reviews

Title or Abstract	Type	Sponsor/Event	Date/Year	Location
Bioelectrochemistry and Biological Electron Transfer Symposium	Lecture	American Chemical Society Meeting	2000	San Francisco, California
Microsomes, Drug Oxidation, and Clinical Pharmacology	Lecture		1997	Berlin, Germany
Is There a Real Risk to Human Health?	Lecture	Chilean Biological Society Meeting Symposium	1994	Puyehue, Chile
Chemistry of P-450	Lecture	All Union Conference	1989	Yalta, USSR
Chemistry and Physics of Cytochrome P-450	Lecture	Yamada Conference on Cytochrome P-450	1987	Nara, Japan
Cytochrome P-450 and Environment	Lecture		1987	Novosibirsk, USSR
Biological Reactive Intermediates	Lecture		1985	College Park, Maryland
Comparative Biochemistry	Lecture		1985	Beerse, Belgium
Biophysics and Induction of Cytochrome P-450	Plenary Lecture		1985	Budapest, Hungary
Contributions of Toxicology to Risk Assessment and Health Regulation	Lecture		1985	Tübingen, Germany
Microsomes and Drug Oxidations	Lecture		1981	Tokyo, Japan
Biological Reactive Intermediates	Lecture		1980	Surrey, Guilford, Britain
Microsomes and Drug Oxidations	Lecture		1979	Ann Arbor, Michigan
Function of Microsomal Drug Metabolizing Enzymes	Lecture	Stanford University	1972	Stanford, California