News and Publications

Chemical Physiology

B.F. Cravatt, G.C. Adam, M.H. Bracey, K. Chiang, A. Clement, M. Evans, G. Hawkin, M. Humphrey, N. Jessani, K. Kustedjo, Y. Liu, K. Matsuda, M. McKinney, A. Speers

We are interested in understanding complex physiology and behavior at the level of chemistry and molecules. At the center of cross talk between different physiologic processes are endogenous compounds that provide a molecular mode for intersystem communication. However, many of these molecular messages remain unknown, and even in the instances in which the participating molecules have been defined, the mechanisms by which these compounds function are mostly still a mystery.

Part of our efforts focus on a family of chemical messengers termed the fatty acid amides, which affect many physiologic functions, including sleep and pain. In particular, one member of this family, oleamide, accumulates selectively in the cerebrospinal fluid of tired animals. This finding suggests that oleamide may function as a molecular indicator of an organism's need for sleep. Another fatty acid amide, anandamide, may be an endogenous ligand for the cannabinoid receptor in the brain.

The in vivo levels of chemical messengers such as the fatty acid amides must be tightly regulated to maintain proper control over the influence of the messengers on brain and body physiology. We are characterizing a mechanism by which the level of fatty acid amides can be regulated in vivo. Fatty acid amide hydrolase degrades the fatty acid amides to inactive metabolites (Fig. 1). Thus, the hydrolase effectively terminates the signaling messages conveyed by fatty acid amides, possibly ensuring that these molecules do not generate physiologic responses in excess of their intended purpose.

We are using transgenic and synthetic chemistry techniques to study the role of the hydrolase in the regulation of fatty acid amide levels in vivo. In collaboration with R.C. Stevens, Department of Molecular Biology, we aim to solve the 3-dimensional structure of fatty acid amide hydrolase. We are also interested in proteins responsible for the biosynthesis of fatty acid amides.

Another area of interest is the design and use of chemical probes for the global analysis of protein function. The evolving field of proteomics, defined as the simultaneous analysis of the complete protein content of a given cell or tissue, encompasses considerable conceptual and technical challenges. We hope to enhance the quality of information obtained from proteomics experiments by using chemical probes that indicate the collective catalytic activities of entire classes of enzymes. These probes could be used to record variations in protein function independent of alterations in protein abundance and would be a powerful and complimentary set of tools for proteome analysis.

We succeeded in generating one such chemical reagent, FP-biotin, which targets the serine hydrolases, a large family of enzymes composed of numerous proteases, lipases, esterases, and amidases. We are using FP-biotin to explore the roles of serine hydrolases in variety of physiologic and pathologic processes. Additionally, in an ongoing collaboration with E.J. Sorensen, Department of Chemistry, we are designing and testing chemical probes that target other enzyme families to expand our capacity to profile proteins in an activity-based manner.

PUBLICATIONS

Adam, G.C., Sorensen, E.J., Cravatt, B.F. Proteomic profiling of mechanistically distinct enzyme classes using a common chemotype. Nat. Biotechnol. 20:805, 2002.

Huitrón-Reséndiz, S., Gombart, L., Cravatt, B.F., Henriksen, S.J. Effect of oleamide on sleep and its relationship to blood pressure, body temperature, and locomotor activity in rats. Exp. Neurol. 172:235, 2001.

Jessani, N., Liu, Y., Humphrey, M., Cravatt, B.F. Enzyme activity profiles of the secreted and membrane proteome that depict cancer cell invasiveness. Proc. Natl. Acad. Sci. U. S. A. 99:10335, 2002.

Larsen, N.A., Heine, A., Crane, L., Cravatt, B.F., Lerner, R.A., Wilson, I.A. Structural basis for a disfavored elimination reaction in catalytic antibody 1D4. J. Mol. Biol. 314:93, 2001.

Lichtman, A.H., Hawkins, E.G., Griffin, G., Cravatt, B.F. Pharmacological activity of fatty acid amides is regulated, but not mediated, by fatty acid amide hydrolase in vivo. J. Pharmacol. Exp. Ther. 302:73, 2002.

Sipe, J.C., Chiang, K., Gerber, A., Beutler, E., Cravatt, B.F. A missense mutation in human fatty acid amide hydrolase associated with problem drug use. Proc. Natl. Acad. Sci. U. S. A. 99:8394, 2002.