Effect of lithium salts on lactate dehydrogenase, adenylate kinase, and 1-phosphofructokinase activities.
Inhibitions of 30 nM rabbit muscle 1-phosphofructokinase (PFK-1) by lithium, potassium, and sodium salts showed inhibition or not depending upon the anion present. Generally, potassium salts were more potent inhibitors than sodium salts; the extent of inhibition by lithium salts also varied with the anion. Li(2)CO(3) was a relatively potent inhibitor of PFK-1 but LiCl and lithium acetate were not. Our results suggest that extents of inhibition by monovalent salts were due to both cations and anions, and the latter needs to be considered before inhibition can be credited to the cation. An explanation for monovalent salt inhibitions is proffered involving interactions of both cations and anions at negative and positive sites of PFK-1 that affect enzyme activity. Our studies suggest that lithium cations per se are not inhibitors: the inhibitors are the lithium salts, and we suggest that in vitro studies involving the effects of monovalent salts on enzymes should involve more than one anion.
Russell
Percy
P
Department of Biology, University of California-San Diego, La Jolla, CA, USA. prussell@ucsd.edu
Williams
Anita
A
Abbott
Ami
A
Chadwick
Jessica
J
Ehya
Farnaz
F
Flores
Roxana
R
Hardamon
Chanae
C
D000263:Adenylate Kinase / Q000187:drug effects*; D000818:Animals; D000838:Anions / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000187:drug effects*; D008094:Lithium / Q000494:pharmacology*; D018482:Muscle, Skeletal / Q000201:enzymology; D010732:Phosphofructokinase-1 / Q000187:drug effects*; D011188:Potassium; D011817:Rabbits; D012492:Salts / Q000494:pharmacology*; D012964:Sodium
D000838:Anions; D004791:Enzyme Inhibitors; D012492:Salts; D008094:Lithium; D012964:Sodium; D007770:L-Lactate Dehydrogenase; D010732:Phosphofructokinase-1; C068652:1-phosphofructokinase; D000263:Adenylate Kinase; D011188:Potassium