Matt Traylor.

Graduate Student
University of California, Berkeley

B.S. Chemical Engineering, 2005
Purdue University

Office Location: 497A Tan Hall
Office Telephone: 510-643-8340
Office Fax: 510-643-1228

Characterizing the effect of microenvironment on human cytochrome P450 catalysis

The cytochromes P450 comprise a superfamily of heme-thiolate monooxygenases of great physiological relevance. In animals, these enzymes are found in many types of tissue and perform a diverse number of roles. One key role in humans is the metabolism of the majority of currently prescribed drugs. Hydrophilic compounds are water soluble so they will be easily excreted, however, hydrophobic drug compounds can build up in the body causing harm to the tissue. The P450 enzymatic system contains a reductase coenzyme, which shuttles electrons from NADPH to the P450. These electrons activate dissolved dioxygen to functionalize hydrophobic compounds in a variety of ways to make them more hydrophilic. The metabolite that is generated can be directly excreted, further reacted by a different P450 enzyme, or coupled to a hydrophilic compound and excreted.

Figure 1: Generalized picture of the microsomal P450 system

The cytochromes P450 have a large industrial potential in two fields. First, there is an obvious relevance to the pharmaceutical industry for toxicity and metabolism tests. Also, P450s are attractive to the field of biotechnology due to their ability to perform oxidative chemistry on traditionally difficult sites to modify. The P450’s industrial promise is rendered impractical, however, due to slow reaction rates, low stability, and low efficiency.My research is currently focused on understanding the relationship between a P450s environment and its function with an emphasis on increasing stability, efficiency, and reaction rate. Within the P450 reaction scheme, as shown below, there are several branch points leading to uncoupling pathways. These pathways drain electrons from the system decreasing the reaction efficiency and rate of product formation. Also, the uncoupled product is often a reactive oxygen compound capable of inactivating the protein. It is clear that the uncoupling mechanism is crucial to the practicality of a P450 system. As such, it is important to understand what environmental factors can influence the extent of uncoupling and to optimize these parameters yielding a more efficient, longer lasting enzymatic system that is still intrinsically unmodified and relevant from a pharmaceutical perspective.

Figure 2: P450 reaction cycle