RT Journal Article
SR Electronic
T1 Phosphofructokinase from the Liver Fluke <em>Fasciola hepatica</em>
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 161
OP 176
VO 3
IS 2
A1 DEBORAH BENNETT STONE
A1 TAG E. MANSOUR
YR 1967
UL http://molpharm.aspetjournals.org/content/3/2/161.abstract
AB Phosphofructokinase from the liver fluke Fasciola hepatica has been isolated in an inactive form by a procedure involving differential centrifugation. The inactive enzyme could be activated by a combination of adenosine 3',5'-phosphate (cyclic 3',5'-AMP) and a thermostable fraction obtained from the incubation of a heavy particulate fraction with ATP and Mg++. Analysis of the thermostable fraction demonstrated that Mg++, ADP, and inorganic phosphate in this fraction could account for enzyme activation in the presence of cyclic 3',5'-AMP. Nucleoside triphosphates were found to be nearly as effective as ADP while inorganic phosphate could be replaced by sulfate anions or hexose phosphates. Activation of the fluke enzyme was found to be readily reversible by dialysis. Sucrose gradient ultracentrifugal analysis of the enzyme before and after activation gave an S20,w of 5.5 S for the inactive enzyme and 12.8 S for the activated enzyme, suggesting the involvement of a monomer-polymer system. Anallysis of the rate of activation data suggests that the activation process behaves like a first-order reaction. Serotonin (5-hydroxytryptamine) when incubated with the heavy particulate fraction and ATP/Mg++ resulted in the formation of a thermostable fraction which can activate inactive phosphofructokinase in the absence of cyclic 3',5'-AMP. The evidence indicates that serotonin activates this enzyme through the action of cyclic 3',5'-AMP. ACKNOWLEDGMENTS This work was supported by Research Grant AI04214 from the National Institute of Allergy and Infectious Diseases, U. S. Public Health Service; and a Research Career Development Award GM-K3-3848 from the Division of General Medical Sciences, U. S. Public Health Service.