Estrada Receiving Early Career Research Award

By Dirk Hoffman

Estrada has been named the recipient of ASPET’s 2025 Richard Okita Early Career Award in Drug Metabolism and Disposition in recognition for his innovative research and pioneering use of 19F-NMR spectroscopy techniques to provide new insights into cytochrome P450 redox partner structural dynamics, substrate binding, metabolism and allosteric enzyme inhibition.

The ASPET award recognizes outstanding original research contributions in drug metabolism and disposition, particularly those having a major impact on future research in the field.  

“This award is an incredible honor. The award is unusual from most research awards in that it is named after a program officer at the National Institutes of Health, Dr. Richard Okita, whose record of dedicated service to support junior scientists in my field is legendary,” Estrada says.

“The award is also personal, since Dr. Okita played a pivotal role in my own development as an independent scientist,” Estrada says.

Estrada first became interested in P450 enzymes as a postdoctoral scientist while training in the lab of Emily Scott, PhD, at the University of Kansas.

The Scott lab was interested in understanding how the steroidogenic P450 enzyme (and prostate cancer drug target) CYP17A1 is regulated. Estrada had previously trained in NMR spectroscopy as a graduate student and was brought in specifically to apply this technique toward CYP17A1.

“While working on this project, I became fascinated by the fact that all P450 enzymes, regardless of their source (animal, plant, or fungus) or chemical composition, adopt a very similar three-dimensional structure,” Estrada says. “I realized that by understanding one of these enzymes in depth, one could gain insight into other P450 enzymes, including those that perform drug metabolism in humans.”

Estrada says the overall goal of his lab’s research is to understand how enzymes from the cytochrome P450 class function on a molecular level.

The enzymes his lab investigates are very diverse and include those that metabolize vitamin D and cholesterol in mammals, as well as P450 enzymes from pathogenic bacteria that are candidate drug targets.

“One of the key findings from our work is that some of the coordinated movements in these enzymes are evolutionarily preserved between bacteria and mammals, which speaks to their importance in biology,” Estrada says.

One of the main tools in his research is fluorine nuclear magnetic resonance (NMR) spectroscopy. Fluorine labeling of proteins is a long-standing technique, but until recently had never been applied toward the study of P450 enzymes.

“This technique allows us to monitor the motions of these important enzymes while circumventing limitations from the large size of the proteins, which is typically an obstacle in traditional NMR spectroscopy,” Estrada says. “Some of the motions and changes in structure are extremely subtle and are often missed using other structural techniques.”

“We are able to complement these experiments with other biochemical techniques in the lab to provide a holistic picture of P450 function.”

The Estrada lab’s research includes characterizing the substrate and redox partner interactions of the enzymes responsible for activating and deactivating vitamin D.

“Vitamin D is an important hormone that, among other things, helps regulate the absorption of essential nutrients from our diet,” he says. “An estimated one-fourth of the U.S. population is deficient in Vitamin D.”

“However, we still don’t fully understand how effective vitamin D supplementation is. Vitamin D itself signals our bodies to produce more of the P450 enzyme, CYP24A1, that inactivates vitamin D,” Estrada adds. “It’s a kind of feedback loop that protects us from vitamin D toxicity. One of the original goals in my lab was to understand how CYP24A1 is regulated, which we expect will open the door for targeted vitamin D related therapies.”

Estrada says an important finding from his lab was the discovery that small changes in the structure of vitamin D can have a large impact on the way it is recognized and broken down by CYP24A1.

A parallel effort in the lab is the structural study of the enzyme CYP121 of Mycobacterium tuberculosis, the disease-causing pathogen in tuberculosis (TB).

The bacterium that causes tuberculosis makes 20 cytochrome P450 enzymes, although the function of each of these is still being investigated, Estrada says.

“We’re interested in the enzyme CYP121, which is considered essential for the viability of the organism and has been targeted extensively for drug design,” he adds. “However, a major concern is whether a hypothetical CYP121 drug would incidentally bind to human drug metabolizing P450 enzymes. This could have dire consequences, since patients undergoing tuberculosis treatments are already taking an aggressive regiment of medications.”

The lab recently discovered that CYP121 function relies on its ability to self-associate as a pair (or a dimer), according to Estrada, and the researchers are currently investigating this feature of the enzyme to determine whether it presents an opportunity to target CYP121 function while reducing the possibility of drug-induced toxicities.

Estrada will receive the 2025 Richard Okita Early Career Award in Drug Metabolism and Disposition April 6 during the ASPET 2025 annual meeting in Portland, Oregon, where he will also present a lecture titled “Art of the Subtle: How Small Changes in Structure Can Have a Big Impact on Cytochrome P450 Function.”