title: Isolation and characterization of phosphofructokinase C from rabbit brain.
abstract: Phosphofructokinase from rabbit brain consists of hybrids of the A, B, and C isozymes. Phosphofructokinase C was isolated from a purified mixture of such hybrids in a 2-step procedure. In the first step, phosphofructokinase B was removed by chromatography on DEAE-Sephadex. In the second step, subunits of phosphofructokinases A and C were separated by dissociation at pH 5.0 followed by chromatography on carboxymethylcellulose. The separated isozymes were then reassociated by neutralization. Phosphofructokinase C was structurally distinct from phosphofructokinases A (obtained from muscle or brain) and B (obtained from liver) as shown by one-dimensional chymotryptic and staphylococcal V8 protease fingerprints of all three isozymes. In addition, phosphofructokinase C cross-reacted weakly or not at all with antisera raised against phosphofructokinase B or phosphofructokinase A. Phosphofructokinase C was also kinetically distinct from the A and B isozymes. The C isozyme was more sensitive than the A isozyme but less sensitive than the B isozyme to inhibition by ATP, was less sensitive than the A isozyme but more sensitive than the B isozyme to inhibition by citrate, and was less sensitive than either of the other two isozymes to activation by inorganic phosphate, AMP, and fructose 2,6-bisphosphate. The self-association properties of phosphofructokinase C differed from those of the A and B isozymes in that at pH 8.0, the C isozyme did not form oligomers larger than a tetramer under conditions where the other two isozymes did. Thus the properties of phosphofructokinase C are in general quite distinct from those of the other two phosphofructokinase isozymes.
authors.forename: L G
authors.initials: LG
authors.lastname: Foe
authors.forename: R G
authors.initials: RG
authors.lastname: Kemp
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002852:Chromatography, Ion Exchange; D002918:Chymotrypsin / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism; D004789:Enzyme Activation; D005635:Fructosediphosphates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D010710:Phosphates / Q000378:metabolism; D010732:Phosphofructokinase-1 / Q000302:isolation & purification*; D011817:Rabbits; D012697:Serine Endopeptidases
chemical_list: D005635:Fructosediphosphates; D007527:Isoenzymes; D010710:Phosphates; D000249:Adenosine Monophosphate; C027652:fructose 2,6-diphosphate; D010732:Phosphofructokinase-1; D010450:Endopeptidases; D012697:Serine Endopeptidases; D002918:Chymotrypsin; C028344:glutamyl endopeptidase