Ornithine decarboxylase and S-adenosyl methionine decarboxylase in skin fibroblasts of normal and cystic fibrosis patients.

The key enzymes in the synthesis of the naturally occurring polyamines, ornithine 
decarboxylase (ODC) and S-adenosyl methionine (SAM) decarboxylase, were investigated during cell 
growth and aging in fibroblast cultures from normal patients and patients 
with cystic fibrosis. A linear correlation between increased S-adenosyl methionine activity 
and putrescine concentration was apparent in all cell lines. A putrescine 
concentration of 0.8 mM was optimal for enhancement of SAM decarboxylase 
activity. The passage number of the cell line correlated inversely with 
maximal putrescine-stimulated SAM decarboxylase activity, earlier passage numbers having the highest 
specific activity (Fig. 1). No significant differences in basal or putrescine-stimulated 
SAM decarboxylase activity were noted between normal fibroblast cultures and cells 
from patients with cystic fibrosis (Fig. 2). SAM decarboxylase activity increased 
as the cell lines approached confluence. Activity was lowest during exponential 
growth (Fig. 3). ODC activity was increased during early exponential growth 
and fell as cells reached confluence (Fig. 4). No differences in 
ODC activity and putrescine inhibition between the normal and cystic fibrosis 
cell cultures at equivalent points of exponential growth were noted. 