J. Biol. Chem., Vol. 260, Issue 30, 16099-16105, Dec, 1985
Comparative purification and characterization of invertebrate muscle glycogen synthase from the porcine parasite Ascaris suum
LL Hannigan, MJ Donahue and RA Masaracchia
Glycogen synthase has been purified from the obliquely striated muscle of
the swine parasite Ascaris suum. The muscle contains a concentration of
glycogen synthase and glycogen which is 20-fold and 15-fold, respectively,
greater than rabbit skeletal muscle. The enzyme could not be solubilized
with salivary amylase, but partial solubilization was achieved by
activation of endogenous phosphorylase. The enzyme was purified to 85-90%
homogeneity (specific activity = 4.3 units/mg) by DEAE-cellulose, Sepharose
4B, and glucosamine 6-phosphate chromatography. The purified glycogen
synthase was substantially similar to rabbit skeletal muscle enzyme with
respect to Mr (gel electrophoresis and gel filtration), pH dependence,
aggregation properties, temperature dependence, and kinetic constants for
substrates and activators. Glycogen synthase I was converted to glycogen
synthase D by the cyclic AMP-dependent protein kinase. The cyclic
AMP-dependent protein kinase catalyzed the incorporation of 1.3 mol of
phosphate into each glycogen synthase I subunit and the concomitant
interconversion to glycogen synthase D. Since glycogen is the sole fuel
utilized by this organism during nonfeeding periods of the host, the
characterization of this enzyme provides further insight into the
regulatory mechanisms which determine glycogen turnover.
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