title: Putrescine and spermidine sensitivity of lysine decarboxylase in Escherichia coli: evidence for a constitutive enzyme and its mode of regulation.
abstract: Cells of Escherichia coli grown under physiological (noninducing) conditions have a low level of lysine decarboxylase activity. This activity differs from the enzyme found in induced cells in its sensitivity to putrescine (33% of control in the presence of 20 mM putrescine). It is also sensitive to spermidine (20% of control in the presence of 6 mM spermidine). A mixture of putrescine and spermidine completely eliminated lysine decarboxylase activity. This provides evidence for the existence of a biosynthetic enzyme and suggests a mechanism to explain the appearance of cadaverine in polyamine-depleted cells.
mesh_terms: D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism*; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D011700:Putrescine / Q000494:pharmacology*; D013095:Spermidine / Q000494:pharmacology*
chemical_list: D002262:Carboxy-Lyases; C021520:lysine decarboxylase; D013095:Spermidine; D011700:Putrescine