Abstract
Triethylenetetramine (TETA) is an efficient copper chelator that has versatile clinical potential. We have recently shown that spermidine/spermine-N1-acetyltransferase (SSAT1), the key polyamine catabolic enzyme, acetylates TETA in vitro. Here, we studied the metabolism of TETA in three different mouse lines: syngenic, SSAT1-overexpressing, and SSAT1-deficient (SSAT1-KO) mice. The mice were sacrificed at 1, 2, or 4 h after TETA injection (300 mg/kg i.p.). We found only N1-acetyltriethylenetetramine (N1AcTETA) and/or TETA in the liver, kidney, and plasma samples. As expected, SSAT1-overexpressing mice acetylated TETA at an accelerated rate compared with syngenic and SSAT1-KO mice. It is noteworthy that SSAT1-KO mice metabolized TETA as syngenic mice did, probably by thialysine acetyltransferase, which had a Km value of 2.5 ± 0.3 mM and a kcat value of 1.3 s−1 for TETA when tested in vitro with the human recombinant enzyme. Thus, the present results suggest that there are at least two N-acetylases potentially metabolizing TETA. However, their physiological significance for TETA acetylation requires further studies. Furthermore, we detected chemical intramolecular N-acetyl migration from the N1 to N3 position of N1AcTETA and N1,N8-diacetyltriethylenetetramine in an acidified high-performance liquid chromatography sample matrix. The complex metabolism of TETA together with the intramolecular N-acetyl migration may explain the huge individual variations in the acetylation rate of TETA reported earlier.
Footnotes
This work was supported in part by grants from the Intramural Research Program of the National Institutes of Health National Institute of Dental and Craniofacial Research; the Academy of Finland; the North Savo Regional Fund of the Finnish Cultural Foundation; and the University of Eastern Finland strategic funding.
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
doi:10.1124/dmd.111.041798.
↵ The online version of this article (available at http://dmd.aspetjournals.org) contains supplemental material.
-
ABBREVIATIONS:
- TETA
- triethylenetetramine (1,8-diamino-3,6-diazaoctane)
- HFBA
- heptafluorobutyric acid
- N1AcTETA
- N1-monoacetyltriethylenetetramine
- N3AcTETA
- N3-monoacetyltriethylenetetramine
- N1N8DiAcTETA
- N1,N8-diacetyltriethylenetetramine
- PBS
- phosphate-buffered saline
- Spd
- spermidine
- Spm
- spermine
- SSA
- sulfosalisylic acid
- SSAT1
- spermidine/spermine N1-acetyltransferase
- hSSAT1
- human spermidine/spermine N1-acetyltransferase
- SSAT2
- thialysine acetyltransferase
- SSAT1-KO
- SSAT1 deficient
- HPLC
- high-performance liquid chromatography
- LC-MS
- liquid chromatography-mass spectrometry
- LC-MS/MS
- liquid chromatography-tandem mass spectrometry
- SpmTrien
- 1,12-diamino-3,6,9-triazadodecane
- FID
- free induction decay
- TOF
- time of flight.
- Received July 12, 2011.
- Accepted August 30, 2011.
- U.S. Government work not protected by U.S. copyright
DMD articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|