Understanding the chemical perspectives of enzymes and their medical applications




Past Group Pictures





















Former members

Visiting Faculty

Professor Cynthia Strong

Cindy Strong is a visitor in the Kohen group for the fall of 2014, while she is on sabbatical from her position as Professor of Chemistry at Cornell College.  Cindy grew up on Whidbey Island in Washington state, completed a bachelor's degree at Whitman College, and earned her PhD in chemistry at Caltech.  Cindy's research at Cornell College has focused on metalloproteins, including human copper-zinc superoxide dismutase and rusticyanin, an acid-stable blue copper protein.


Postdoctoral Scholar

Muhammad Saeed

     Dr. Muhammad Saeed was born in a small town near Lahore (Punjab) Pakistan. He got BSc. and MSc. degree in Chemistry from the University of the Punjab Lahore and then got DAAD scholarship to conduct Ph.D in synthetic organic chemistry from Tuebingen University in Germany under the supervision of Prof. Wolfgang Voelter. Before joining Dr. Kohen's group in Nov 2009, he has worked as a postdoc at the University of Nebraska Medical Center, Omaha, where he got training in chemical carcinogenesis. Currently he is using human cancer cell lines to establish new clinical methods based on the findings of Kohen's research team.

Laura Perissinotti

LauraDr. Laura Perissinotti joined the Kohen group in Spring 2010 as a postdoc scholar. Now she is living in Canada, and works as a consultant scholar for the Kohen group.


Anatoly Chernyshev

Dr. Anatoly Chernyshev was a postdoctoral researcher studying nitrogenase, the first enzyme in a pathway of microbial nitrogen assimilation. He was born in Saratov, Russia, received his PhD from Saratov State University and eventually joined the Kohen group in September 2003. This specimen of H. sapiens describes himself as extremely humble and shy (Really?!--says the current website manager), so that general patterns of his social behavior are still scarcely known. Those few things found to the date about Anatoly are sketched at his website or one may get in touch with him via E-mail at a_chernyshev@yahoo.com.



Cornelia Mihai

Cornelia is an Assistant Professor of Organic Chemistry at Northwetern Okalhoma State University. She was born in Bucharest, Romania. She received her B.S. degree in Chemical Engineering from Polytechnic Institute of Bucharest. After that, she was working as a chemical engineer and then as a Research Scientist at the Food Chemistry Institute and at the Institute of Oncology in Bucharest. In 1994 she started her graduate studies in United States and she received her M.S. degree in Chemistry in 1996 and her Ph.D. degree in Medicinal Chemistry in 2001 from University of Illinois at Chicago. After that she was working as Research Associate at Albany Molecular Research, Inc. and as Research Scientist at Integrated DNA Technologies in Coralville, Iowa. In 2002, she took the position as a Postdoctoral Associate in the Kohen group. Currently, she is working on expressing and purifying the enzymes needed for kinetic and structural studies. Her research interests are Bioorganic Chemistry, Medicinal Chemistry and Synthetic Enzymology and she enjoys studying the mechanism, structure and dynamics of the enzymes that are targets for therapeutic drugs. new URL: http://www.nwosu.edu/science/.


Amandeep Sra

Amandeep Kaur Sra was born in Mumbai (Bombay), India. She received her Bachelor of Science and Master of Science degrees in chemistry from the University of Mumbai. For her Ph.D. in Chemistry at the University of Mumbai, she worked on the design and study of molecular magnetic materials with Dr. J.V. Yakhmi, B.A.R.C., India and with Prof. O. Kahn, ICMCB, France. She received the Young Scientist award '99 in Physical Chemistry at the International Symposium of the Indian Chemical Society. Amandeep worked on establishing the vacuum apparatus enabling the study of nitrogenase. After many laborious hours she managed to measure competitive KIEs for this system. Aman has ventured off for her second post-doc at Texas A&M.

Graduate Students

Thelma Abeysinghe

  Thelma joined the Kohen group in fall 2009. She completed her B.Sc. special degree in Chemistry in 2004 at the University of Kelaniya, Sri Lanka. She obtained her M.Sc. degree in Analytical Chemistry from the University of Colombo, Sri Lanka in 2009. Her research concerns are Bio-analytical and Biochemistry. Her hobbies include listening to music, watching films and reading books during leisure time.

Tatiana Mishanina

     Tatiana grew up in a town in Tajikistan and came half-way around the world to Kansas to study Chemistry. She joined the awesome Kohen's lab in December 2008 and started to work on the flavin-dependent thymidylate synthase project. In her free time, she likes to watch comedies, play tennis, or teach her friends Russian.

Daniel Roston

  Daniel Roston Daniel grew up in the suburbs north of Chicago and graduated from Hamilton College in Clinton, NY with a chemistry degree in 2007. He joined the Kohen group in the fall of 2007 and has been combining measurements of kinetic isotope effects in alcohol dehydrogenase with some theoretical modeling to figure out how enzymes work. He is very interested in how quantum mechanics and dynamics affect the course of chemical reactions. When he is not in the lab, Daniel likes to play rugby and read about the crazy ideas physicists are cooking up these days. When he grows up, Daniel wants to be an astronaut. For real.

Eric Koehn

 Eric joined the Kohen group as a graduate student in Spring 2008. Before that, he had been working in this group as a undergraduate student since 2006.

Vanja Stojkovic

 Vanja is a graduate student that joined the Kohen group in Nov 2006.



Zhen Wang

  Zhen Wang (Jen) Born in a small town in Shandong Province, I'm a typical North Chinese girl, who is easy-going and laughs a lot. I decided to become a scientist when I was a little child, dreaming about making some pills for my parents to take and live forever... Ok, that was a funny dream... But I'm still working hard to become a good scientist. After graduating from Nanjing University in 2006, I came to United States. I believe the Ph.D. studies in US will help me to achieve my life legend. My favorite quote is "There are three best things in life--Eating, Sleeping, and Science" by Zhen Wang


Thushani Nilaweera

Thushani Nilaweera graduated from the University of Colombo in Sri Lanka with a Biochemistry and Moleculare Biology Special Degree in 2009 and entered the University of Iowa in the Fall of 2009. She is fascinated with the fields of Oncology and Radiology. Thushani joined the Kohen Research group in the Spring of 2010 and started working on the P.E.T. project.

Arun Sen

ArunArundhuti Sen joined the Kohen group in 2005, after graduating from Knox College in Galesburg, IL. Arun is working on DHFR kinetics, following closely in the footsteps of Lin Wang. She likes to start every day with a loud 'Vive la resistance!' and a short prayer to the gods of the steady-state.

Atsushi Yahashiri

Atsushi Yahashiri was born in Tokyo, Japan. He received His MS degree from Biochemistry Department at UI 2004 and eventually joined the Kohen group in January 2005. Atsushi is currently studying the mechanism of a non-chromosomal DHFR (R67) as potential antibiotic drug for resistance strains of bacteria. He also enjoys the life in Iowa City with his wife and two kids. His hobbies are swimming, mowing lawn, planting fruits and vegetables, going to farmers market (buying), cooking, making good coffee, expressing ADH in vivo, bothering PI with questions, purifying enzymes, blogging, camping, and canoeing with Bryce Plapp (biannual).


Jigar Bandaria

Jigar joined the group in January 2004, and had been working on the Formate Dehydrogenase project. He has received his PhD degree in May 2009, and is now a Postdoc in University of California, Berkeley. jigar@berkeley.edu



Todd Flieschmann

Todd is a graduate student that joined our group in 2004 after finishing a B.S. in Chemistry and Agronomy at Northwest Missouri State University. Todd's current project centers around a newly discovered enzyme denoted Flavin Dependant Thymidylate Synthase. Recently, he has been working on protein expression and purification as well as enzyme mechanism studies. His hobbies include hunting, working on his house and playing with his son. .

Vishal Sharma

Hey, this is Vishal, I did my previous studies at University of Delhi, INDIA. I joined the group in Dec 2006. My interest is to study reaction mechanisms and I aspire to unfold the mysterious steps in enzymatic reactions. In addition to that I like Indian music and I am looking forward to form a music band after graduation. Wish me luck for both of my interests.

Lin Wang

Lin WangLin, joined this group in 2002 and graduated with a PhD in Dec 2006. Currently he is writing a few papers and prepare for his Postdoctoral position.. Before that he spent four years sleeping through classes at Ocean University of Qingdao, P.R.C. and another three years at Zhejiang University, P.R.C.. Lin finds here, in this university, he cannot get enough time for interesting extracurricular activities, which is due to the fact that we have a highly motivated group! His current research focuses on the C-H bond activation project. His main hobbies includes algebra, statistics and software. lin-wang@uiowa.edu

Baoyu Hong

Baoyu HongBaoyu is a graduate student from China and joined this group in summer of 2003. She got B.E. degree in Packaging Engineering in 1999 and M. S. degree in Polymer Science in 2002 from Jilin Unversity, China. Then the same year she came to the Unversity of Iowa. Her current research project is classical TS. At spare time, she loves movies, photography, traveling and celtic music.

Kelli Markham


Dr.Kelli Markham received her Ph.D. in Chemistry in 2004 and was the first to graduate with Ph.D. from the Kohen Group. Kelli's last position in iowa was a visiting Assistant Professor and a Postdoctoral Scholar in the Kohen Group. She receivedher B.A. degree in Chemistry from Lake Forrest College in Illinois in 1998. The summer after her graduation she completed an internship at Abbott Labs in IL. After this, she worked on a project for the DOE, testing for radioactivity (U-235, Tc-99 etc.) in soil and water samples. Kelli entered this university in the Fall of 1999, and since then has worked out the synthesis of key radio-labeled nucleotides for enzyme kinetic studies and completed preliminary KIE studies with DHFR. Currently, Kelli is investigating the chemistry of several enzymes, including:glutamate dehydrogenase and thermophilic dihydrofolate reductase (DHFR). Kelli's hobbies include home remodelling projects with her husband, Dale, and roughhousing with her 150 lb Great Dane, Apollo.


Nitish Agrawal

Nitish Dr. Nitish Agrawal earned his Ph.D in Chemistry in July 2005. He is originally from India. He joined this group in Fall 2001. Nitish loves America. Nitish was born in Aligarh, Uttar Pradesh, in India. He was schooled at Delhi Public School, Mathura Road, New Delhi, India. He received his B.Sc (Honors) degree in Chemistry in 1999 with distinction, and his M.Sc. (Chemistry), specialization in Organic Chemistry in 2001 with distinction from Hindu College, University of Delhi, India. Nitish has qualified National Eligibility Test (NET) in India, which entitles him to join any Public College/University as Lecturer/Research Investigator in India. At UI, he has been a prime researcher on four projects: enzymatic synthesis of labeled nicotinamide cofactor; chemoenzymatic synthesis of labeled derivatives of folic acid; mechanistic studies of E.coli thymidylate synthase (TS); and mechanistic studies of flavin-dependent TS (FDTS). Nitish is currently studying FDTS, which shares no sequence or structure homology with common TS. This is a very high impact type of research since FDTS catalysis is the only path that many biological warfare agents use to synthesize DNA. He has also recently won a prestigious Ph.D fellowship from the Center for Biocatalysis and Bioprocessing (CBB). His general interests and activites include reading and writing articles on science education, traveling, listening to music and playing guitar.


Jocelyn McCracken

JocJocelyn McCracken graduated from Fairfield High School, Fairfield, Iowa in 1996 and majored in chemistry and english while attending Central College in Pella, IA. Jocelyn graduated in the summer of 2002 with a Master's degree and is currently living in the suburbs of Chicago with her husband, Tim, as she searches for employment. We wish her the best of luck and are waiting for a phone call when she makes her first million dollars.




Michael Choi (Deceased)

mac Michael Choi completed my undergraduate studies in chemistry and biochemistry at the University of Washingtong, and began his graduate studies through the University of Iowa's Medical Scientists' training program in 2013. His research studies in the Kohen's group focus on understanding the mechanism of flavin-dependent thymidylate synthase. Outside the laboratory, he enjoyed swimming and food.

Undergraduate Students

Salah Moghram

Salah is an undergrad working with Eric Koehn.

Kyle Wickersham

Mahmoud A Elkhalifa

Christine C Schwartz


 I am from Davenport, Iowa. My first year of college was at Seattle University, and then I transferred to the University of Iowa where I am currently a junior. I am a biology major, chemistry minor, and I am pre-med. I am currently working on a breast cancer experiment doing cell culture and estrogen metabolite extractions to look at DNA methylation patterns. My hobbies include traveling, spending time with friends, and assistant coaching a competitive cheerleading team that I was on for over 5 years. 

Daniel T Watson

Malia Moore

MaMalia Moore graduated from Hope High School (in Hope, Kansas) in 1996 and received her B.S. in chemistry in 2000 from University of Rochester in Rochester, NY. Malia graduated the summer of 2002 from this group with a Master's and is curently in medical school at KU. We wish her the best of luck in all of her future endeavors.





Michael Toraason

MichaelMichael started working in Kohen lab as an undergrad since the summer of 2009. He is studying Chemical Engineering and Computer Science. He will be a senior next year (2011), but will not graduate until 2012. He likes all sports, music, and chillin' with friends. He was born in Chicago but moved to a small Illinois town when He was younger, and has lived there ever since.

Jordan Koehn

JordanJordan started working in Kohen lab as an undergrad during the summer of 2009.

Asad Hashmi

AsadAsad worked with Asushi as an undergrad in Kohen lab in 2009.

Calvin Luzum

CalvinCalvin worked with Zhen Wang as an undergrad in Kohen lab in 2009.

Robert Nixon

RobertRobert was an undergraduate working with Atsushi Yahashiri.

Laura Tvedte

MichaelLaura is an undergrad working in the Kohen group during the summer of 2010. She will be a senior Chemistry major at Truman State University in the fall. In the Kohen group, she is investigating inhibitor activity of a series of compounds with different enzymes. In her free time, she loves to read, practice her French, and spend time with her family and her cat, Frannie.

Erika Torres

MichaelErika started working in Kohen group as an undergrad since the summer of 2010.

Angela Torres

MichaelAngela started working in Kohen group as an undergrad since the summer of 2010.

Hyun Jo (Charlie)

Charlie Charlie was a undergraduate who worked in the Kohen group in 2008.

Majd Haddad

Majd was born in Brest, France original from Lattakia, Syria. He lived in different countries and decided to continue his college education in the United States. Currently, he was a junior majoring in Biochemistry and an Iowa Biosciences Advantage scholar when he joined Kohen group. Now he's a student in Dental school in University of Iowa.


Melissa Hall

Melissa was a graduate student Jan-Dec 2006.


Aaron Mason

Aaron Mason completed his undergraduate work at Cornell College (2005) with a double major in Chemistry and Biochemistry. His was in the Biosciences Program at the University of Iowa and was rotating through the Kohen Lab. Aaron was studying a flavin dependent thymidylate synthase.

Scott Tharp

Scott is a talented undergraduate who joined the group in the Summer of 2003. One can often hear Scott talking to himself as he does injection after injection on the HPLC. We consider this normal behavior so please do not feel frightened. He is now a DDC student.


Pierre Charly Point Du Jour

Pierre Charly Point Du Jour was born in Cayes, Haiti. Pierre lives in New York City with his parents whereas he attends Florida Memorial University pursuing his undergraduate studies in biology and chemistry. Planning to attend the Medical Scientist Training Program (MSTP) at the University of Iowa, through the AGEP Program in summer 2004, Pierre worked with the Eyeman Group on ÒSurface Deposition of Single-Site Redox Reactant.Ó This summer 2005, Pierre has joined the Kohen Group while working on ÒMechanistic Studies of Hydride Transfer Catalyzed by E. coli Thymidylate Synthase W80M Mutant.Ó Pierre has not only done science, but he is also a poet/playwright and some of his works can read on his website (www.jeanpointdujour.org) or you may contact him via email at pcpdj@yahoo.com


Wilmarie Santana

Wilmarie Santana is a sophomore student from University of Puerto Rico-Bayamon working inthe Kohen group on a SROP fellowship.




Steve Sikorski

Steve was a post-doc in the Kohen group who received his Bachelor Degree at Bradley University in Peoria and his PhD here at the University of Iowa with Dr. Dan Quinn, working on acetylcholinesterase and low-barrier hydrogen bonds. He has worked at both the U.S. Department of Agriculture and Walter Reed Army Institute. Steve also became a lecturer here at the University of Iowa teaching Organic Chemistry laboratory and Organic and General Chemistry courses, for one year before returning to research. While with the Kohen group Steve studied temperature dependencies on KIEÕs for dihydrofolate reductase. Steve is now holds an industrial position for a company in Springfield, MO.


Carla Asbury

Carla was an undergraduate in the group, working on improving HPLC separations for KIE studies.






Lena Rydberg

Lena was an undergraduate in our lab, from the Department of Biochemistry here at the University of Iowa. Lena worked in our lab for a summer doing synthesis of deuterated substrates.






Jeff Smith

Jeff is an undergraduate student from Burlington, Iowa. He was responsible (among other things) for the web page, and installing any and every new fancy piece of equipment. He graduated in December 2000 with a B.S. degree in Chemistry with Honors. Currently, we have no news as to his whereabouts. Last we heard he was working as a tech for microscopists, here at the University of Iowa where he was treasured as a valuable asset to their laboratory. If you or anyone you know has any information about the location of Jeff Smith, please call America's Most Wanted immediately and then let us know. Do not attempt any communication with this person, you can tell from his picture just the types of evil deeds he is capable of.


Tim Strutzenberg

Tim is from the Des Moines area and is studying Biochemistry and Chemistry. He is interested in graduate school for pharmacy or to study medicinal and natural products. In his free time, Tim likes to read, bike, and travel the country playing ultimate frisbee with the Iowa Hawkeye Ultimate Club.

Ariel L. Kleinschmidt

I joined the Kohen lab June of 2014. I am a junior who is studying biochemistry, microbiology, and communications. In addition to this lab I am also the lead lab prep for the undergraduate teaching labs and a member of the McLauren research group. Outside of school I enjoy swing dancing, running, and hiking.

Jonathan D Krueger

Jon is from Berlin, Wisconsin and is an undergraduate who joined the Kohen Group in May 2014. Jon is currently a junior at the University of Iowa and is studying Human Physiology with a pre-pharmacy track. Outside the classroom, he is a member of the club ice hockey team and enjoys hanging out with friends. After completing his undergraduate studies, Jon plans on attending pharmacy school. 




Catherine Suchanek

Catherine is from Iowa City and is an undergrad in the lab. She is studying chemical engineering but is very interested in biology as well. When not in school Catherine likes to do art projects and play sports with friends. 

Tasnia Iqbal

My hometown is Cedar Falls, IA. I just recently joined the Kohen group in August 2014. I am currently a sophomore at the University of Iowa majoring in Human Physiology. I hope to go to medical school after graduating college and someday become a pediatrician.  My interests outside of science include community service, singing, and listening to music. 

Group Pictures from Conferences and Other activities (until 2006)

The group in MECC conference in Chicago Oct. 2006

Lin Wang's Goodbye Party 2

Lin Wang's Goodbye Party 1

At the lake 2006

At the lake 2006

GRC 2006

GRC 2006

Fun at MECC


Lunch in MECC 2001