Regulation of S-adenosyl-L-methionine decarboxylase by 1-aminooxy-3-aminopropane: enzyme kinetics and effects on the enzyme activity in cultured cells

The kinetics of inactivation of adenosylmethionine decarboxylase of rat liver and of baby hamster kidney cells (BHK21/C31) by 1-aminooxy-3-aminopropane was studied. The apparent dissociation constants (Ki) for the hepatic and BHK21/C13 enzymes were 1.5 and 2.0 mM and the times of half-inactivation a...

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Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 1990-03, Vol.107 (3), p.339-342
Main Authors: Hyvönen, T, Eloranta, T O
Format: Article
Language:English
Subjects:
1-aminooxy-3-aminopropane
Adenosylmethionine Decarboxylase - antagonists & inhibitors
Adenosylmethionine Decarboxylase - metabolism
Animals
Carboxy-Lyases - metabolism
Cell Division
Cell-Free System
Cells, Cultured
Cricetinae
Half-Life
kidney
Kidney - metabolism
Kinetics
Liver - cytology
Liver - metabolism
Ornithine Decarboxylase Inhibitors
Propylamines - pharmacology
Putrescine - metabolism
Rats
S-Adenosylmethionine - metabolism
Spermidine - metabolism
Spermidine Synthase - antagonists & inhibitors
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Summary:The kinetics of inactivation of adenosylmethionine decarboxylase of rat liver and of baby hamster kidney cells (BHK21/C31) by 1-aminooxy-3-aminopropane was studied. The apparent dissociation constants (Ki) for the hepatic and BHK21/C13 enzymes were 1.5 and 2.0 mM and the times of half-inactivation at infinite concentration of the inhibitor (tau 1/2) were 1.2 and 3.8 min, respectively. Treatment of BHK21/C13 with 0.5 mM 1-aminooxy-3-aminopropane prevented cell growth and depleted the cells of putrescine and spermidine within 1 day. The depletion of spermidine resulted in increased activity of S-adenosylmethionine decarboxylase which was due, at least partly, to the increase in the half-life of the enzyme activity. Because spermine levels were not significantly affected, it appears that spermidine is the principal feedback regulator of S-adenosylmethionine decarboxylase. So, 1-aminooxy-3-aminopropane is a very weak inhibitor of S-adenosylmethionine decarboxylase and the cellular effects can be correlated primarily with its inhibitory effects on ornithine decarboxylase and spermidine synthase. In cell-free systems, however, 1-aminooxy-3-aminopropane is likely to find use in unraveling the reaction mechanism of S-adenosylmethionine decarboxylase.
ISSN:0021-924X
DOI:10.1093/oxfordjournals.jbchem.a123048