J. Biol. Chem., Vol. 261, Issue 27, 12455-12461, Sep, 1986
Purification and identification of intermediate catabolic products in the in vivo degradation of pig liver phosphofructokinase
T Toda and M Ohashi
Phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, EC
2.7.1.11) was purified to homogeneity from pig livers. Polyclonal antibody
against the enzyme was induced in a rabbit, and the IgG fraction was
obtained by chromatography on a Protein A-Sepharose CL-4B column. The
specific antibody was purified further by immunoaffinity chromatography on
a phosphofructokinase-conjugated affinity column. Intermediate catabolic
products of phosphofructokinase were extracted from fresh pig livers under
conditions of inhibition of proteinases, concentrated by chromatography on
an anti-phosphofructokinase IgG- conjugated affinity column, and purified
by two-dimensional polyacrylamide gel electrophoresis. Their
cross-reactivities to the purified phosphofructokinase were assessed by an
immunoelectrotransfer blot method. The intact form of phosphofructokinase
in pig liver was demonstrated as the major spot of 84 kDa on the blot.
Polypeptides of 68, 64, 56, and 51 kDa showed apparent cross-reactivities
to phosphofructokinase. The structural homology among them was confirmed by
proteinase V8 digestion followed by sodium dodecyl sulfate- polyacrylamide
gel electrophoresis. The possibility of artifacts in preparation was ruled
out by an internal tracer method. Thus, it is concluded that the
predominant isozyme of phosphofructokinase in pig liver (84 kDa) is in vivo
degraded via intermediate catabolic products of 68, 64, 56, and 51 kDa.