Effect of lithium salts on lactate dehydrogenase, adenylate kinase, and 1-phosphofructokinase activities

Abstract

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.

Comparisons of Phosphofructokinases-1 from Rabbit, Chicken, and Fish

“…Our working hypothesis is that ascorbate facilitates storage of glucose as glycogen in resting muscle by inhibiting glycolysis; glycolysis is inhibited through specific inhibitions of muscle PFK-1, LDH, and AK by ascorbate. [1][2][3][4]17 It can be shown that the following enzymes associated with glycolysis are not inhibited by 0. 18 and aldolase [19][20][21] form complexes with contractile proteins that would protect them from inhibition by ascorbate; we view aldolase protection of these enzymes from inhibitions by ascorbate as a microcosm of in situ events.…”

“…17 Previous studies showed that lithium, potassium, and sodium salts of acetate and chloride had little or no inhibitory effect on RPFK-1 while the salts of carbonate and sulfate were substantial inhibitors. 17 The effects of these salts on FPFK-1 and CPFK-1 were investigated. Depending upon the associated anion, monovalent cations show wide extents of inhibitions in Table 2 A Table B for FPFK-1 and CPFK-1, respectively.…”

Spinach aldolase interactions with rabbit, chicken, and fish muscle phosphofructokinase-1

“…show that cm PFK-1 and fm PFK-1 carbonate and sulfate salt inhibitions follow inhibition patterns similar to rm PFK-1 [2,18]. Generally, acetates and chlorides were poor or not inhibitors and carbonates and sulfates were good inhibitors of rm PFK-1.…”

“…It was previously shown that 0.1 molar monovalent carbonates salts or sulfates inhibited rm PFK-1 [2,18]. Tables 1(a) and (b) show percent inhibitions of 30 nM cm PFK-1 and 30 nM fm PFK-1 by monovalent salts; the negative values show the percent stimulation.…”

Inhibition by Ascorbate among Phosphofructokinase-1, Aldolase, Enolase, and Lactate Dehydrogenase in Rabbit Muscle

“…A report by others [7][8] that a AA-fatty acid derivative inhibited cancer growth effects of other AA-fatty acid derivatives on enolase activity. Mutual protection of PFK-1, aldolase, enolase and LDH from inhibitions were investigated.…”