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Characterization of Arginine Decarboxylase in Rat Brain and Liver
Author(s) -
Regunathan S.,
Reis D. J.
Publication year - 2000
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2000.0742201.x
Subject(s) - agmatine , ornithine decarboxylase , arginine decarboxylase , ornithine decarboxylase antizyme , arginine , polyamine , cytosol , biology , mitochondrion , arginase , biochemistry , microbiology and biotechnology , spermine , enzyme , amino acid
We compared the properties of mammalian arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) in rat liver and brain. Mammalian ADC is thermally unstable and associated with mitochondrial membranes. ADC decarboxylates both arginine ( K m = 0.75 m M ) and ornithine ( K m = 0.25 m M ), a reaction not inhibited by the specific ODC inhibitor, difluoromethylornithine. ADC activity is inhibited by Ca 2+ , Co 2+ , and polyamines, is present in many organs being highest in aorta and lowest in testis, and is not recognized by a specific monoclonal antibody to ODC. In contrast, ODC is thermally stable, cytosolic, and mitochondrial and is expressed at low levels in most organs except testis. Although ADC and ODC are expressed in cultured rat C6 glioma cells, the patterns of expression during growth and confluence are very different. We conclude that mammalian ADC differs from ADC isoforms expressed in plants, bacteria, or Caenorhabditis elegans and is distinct from ODC. ADC serves to synthesize agmatine in proximity to mitochondria, an organelle also harboring agmatine's degradative enzyme, agmatinase, and a class of imidazoline receptor (I 2 ) to which agmatine binds with high affinity.