Abstract
The gene EPXH2 encodes for the soluble epoxide hydrolase (sEH), an enzyme involved in the regulation of cardiovascular and renal physiology containing two distinct domains connected via a proline-rich linker. The C-terminal domain containing the EH catalytic activity has been well studied. In contrast, a function for the N-terminal domain, which has high homology to the haloacid dehalogenase family of phosphatases, has not been definitively reported. In this study we describe the N-terminal domain as a functional phosphatase unaffected by a number of classic phosphatase inhibitors. Assuming a functional association between these catalytic activities, dihydroxy lipid phosphates were rationalized as potential endogenous substrates. A series of phosphorylated hydroxy lipids were therefore synthesized and found to be excellent substrates for the human sEH. The best substrate tested was the monophosphate of dihydroxy stearic acid (threo-9/ 10-phosphonoxy-hydroxy-octadecanoic acid) with Km = 21 ± 0.3 μM, VMax = 338 ± 12 nmol·min-1·mg-1, and kcat = 0.35 ± 0.01 s-1. Therefore dihydroxy lipid phosphates are possible candidates for the endogenous substrates of the sEH N-terminal domain, which would represent a novel branch of fatty acid metabolism with potential signaling functions.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1558-1563 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 100 |
| Issue number | 4 |
| DOIs | |
| State | Published - Feb 18 2003 |
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ASJC Scopus subject areas
- Genetics
- General
Cite this
The soluble epoxide hydrolase encoded by EPXH2 is a bifunctional enzyme with novel lipid phosphate phosphatase activity. / Newman, John W.; Morisseau, Christophe; Harris, Todd R.; Hammock, Bruce D.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 100, No. 4, 18.02.2003, p. 1558-1563.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The soluble epoxide hydrolase encoded by EPXH2 is a bifunctional enzyme with novel lipid phosphate phosphatase activity
AU - Newman, John W.
AU - Morisseau, Christophe
AU - Harris, Todd R.
AU - Hammock, Bruce D.
PY - 2003/2/18
Y1 - 2003/2/18
N2 - The gene EPXH2 encodes for the soluble epoxide hydrolase (sEH), an enzyme involved in the regulation of cardiovascular and renal physiology containing two distinct domains connected via a proline-rich linker. The C-terminal domain containing the EH catalytic activity has been well studied. In contrast, a function for the N-terminal domain, which has high homology to the haloacid dehalogenase family of phosphatases, has not been definitively reported. In this study we describe the N-terminal domain as a functional phosphatase unaffected by a number of classic phosphatase inhibitors. Assuming a functional association between these catalytic activities, dihydroxy lipid phosphates were rationalized as potential endogenous substrates. A series of phosphorylated hydroxy lipids were therefore synthesized and found to be excellent substrates for the human sEH. The best substrate tested was the monophosphate of dihydroxy stearic acid (threo-9/ 10-phosphonoxy-hydroxy-octadecanoic acid) with Km = 21 ± 0.3 μM, VMax = 338 ± 12 nmol·min-1·mg-1, and kcat = 0.35 ± 0.01 s-1. Therefore dihydroxy lipid phosphates are possible candidates for the endogenous substrates of the sEH N-terminal domain, which would represent a novel branch of fatty acid metabolism with potential signaling functions.
AB - The gene EPXH2 encodes for the soluble epoxide hydrolase (sEH), an enzyme involved in the regulation of cardiovascular and renal physiology containing two distinct domains connected via a proline-rich linker. The C-terminal domain containing the EH catalytic activity has been well studied. In contrast, a function for the N-terminal domain, which has high homology to the haloacid dehalogenase family of phosphatases, has not been definitively reported. In this study we describe the N-terminal domain as a functional phosphatase unaffected by a number of classic phosphatase inhibitors. Assuming a functional association between these catalytic activities, dihydroxy lipid phosphates were rationalized as potential endogenous substrates. A series of phosphorylated hydroxy lipids were therefore synthesized and found to be excellent substrates for the human sEH. The best substrate tested was the monophosphate of dihydroxy stearic acid (threo-9/ 10-phosphonoxy-hydroxy-octadecanoic acid) with Km = 21 ± 0.3 μM, VMax = 338 ± 12 nmol·min-1·mg-1, and kcat = 0.35 ± 0.01 s-1. Therefore dihydroxy lipid phosphates are possible candidates for the endogenous substrates of the sEH N-terminal domain, which would represent a novel branch of fatty acid metabolism with potential signaling functions.
UR - http://www.scopus.com/inward/record.url?scp=0037452577&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037452577&partnerID=8YFLogxK
U2 - 10.1073/pnas.0437724100
DO - 10.1073/pnas.0437724100
M3 - Article
C2 - 12574510
AN - SCOPUS:0037452577
VL - 100
SP - 1558
EP - 1563
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 4
ER -