Carboxypeptidase A-catalyzed direct conversion of leukotriene C4 to leukotriene F4

Pallu Reddanna, K. Sandeep Prabhu, Jay Whelan, C. Channa Reddy

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19 Scopus citations


Leukotrienes (LTs) are 5-lipoxygenase (5-LO)-derived arachidonic metabolites that constitute a potent set of lipid mediators produced by inflammatory cells. Leukotriene A4, a labile allylic epoxide formed from arachidonic acid by dual 5-LO activity, is the precursor for LTB4 and LTC4 synthesis. LTC4 is further transformed enzymatically by the sequential action of γ-glutamyltranspeptidase and dipeptidase to LTD4 and LTE4, respectively. In this report, we present evidence that bovine pancreatic carboxypeptidase A (CPA), which shares significant sequence homology with CPA in mast cell granules, catalyzes the conversion of LTC4 to LTF4 via the hydrolysis of an amide bond. The identity of CPA-catalyzed LTC4 hydrolysis product as LTF4 was confirmed by several analytical criteria, including enzymatic conversion to conjugated tetraene by soybean LO, conversion to LTE4 by γ-glutamyltranspeptidase, cochromatography with the standard LTF4 and positive-ion fast-atom bombardment mass spectral analysis. Thus, it appears that the physiological significance of this single-step transformation may point toward a major cellular homeostatic mechanism of metabolizing LTC4, a potent bronco- and vasoconstrictor, to a less potent form of cysteinyl LTs.

Original languageEnglish (US)
Pages (from-to)158-163
Number of pages6
JournalArchives of Biochemistry and Biophysics
Issue number2
StatePublished - May 15 2003

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology


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