PMID: 708395Aug 15, 1978Paper

Kinetics of polyamine synthesis and turnover in mouse fibroblasts

The Biochemical Journal
F McCormick


Kinetics of polyamine synthesis and degradation were studied in mouse fibroblasts growing in suspension culture. The approach was to prelabel cells with radioactive polyamines and to observe the rate of loss of radioactivity and the rate of decrease in specific activity of these compounds in cells. Radioactive putrescine declined with a half-life of 1.5-2h, whether derived directly from exogenous putrescine or indirectly from ornithine. Much of this turnover was due to excretion, the kinetics of which suggested that a steady-state was being established between putrescine inside and outside the cells. Within 5h of medium change, cells growing at a density of 5x10(5)cells/ml had supplied putrescine to the medium to a concentration of about 1mum. When cells were prelabelled with either putrescine or spermidine, radioactivity in cell spermidine declined with a half-life of 60h. This rate of turnover is sufficient to provide all the spermine required by the cell. Spermine synthesis was the only observed reaction of spermidine, although some excretion into the growth medium was detected. Spermine was not degraded at a detectable rate as long as cells were growing exponentially; in stationary phase, degradation to spermidine, which wa...Continue Reading


Dec 1, 1999·APMIS : Acta Pathologica, Microbiologica, Et Immunologica Scandinavica·Gunnar Houen
Oct 1, 1983·Cell Biochemistry and Function·J C Allen
Nov 1, 1982·The American Journal of Physiology·D R BethellA E Pegg
Feb 1, 1987·European Journal of Cancer & Clinical Oncology·J P MoulinouxY Chambon

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