Trypsin modification of phosphofructokinase from Ascaris suum.
Phosphofructokinase from Ascaris suum is a tetramer with subunits of 90 kDa. Treatment of the native enzyme with trypsin (10%, w/w) followed by SDS-gel electrophoresis was shown to immediately generate a 40-kDa fragment followed by a gradual formation of two other fragments of 37 and 32 kDa. The loss of catalytic activity during the digestion was less than 50%. Gel filtration of the digested enzyme under non-denaturing conditions showed a Mr almost that of the native enzyme. Digestion of the phosphorylated enzyme resulted in an 80% release of the phosphorylated peptide over the period of 1 h. The digested enzyme was inhibited less by ATP than the native enzyme, but it was still positively affected by the effectors, fructose 2,6-bisphosphate and AMP. The results are interpreted to suggest that the structure of the ascarid phosphofructokinase is similar to that of the mammalian enzyme.
Ahanotu
P A
PA
Department of Biochemistry and Molecular Biology, Texas College of Osteopathic Medicine/University of North Texas, Fort Worth 76107.
Ahanotu
E
E
Srinivasan
N G
NG
Harris
B G
BG
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001200:Ascaris / Q000187:drug effects / Q000201:enzymology*; D001665:Binding Sites; D005260:Female; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D010732:Phosphofructokinase-1 / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D014357:Trypsin / Q000378:metabolism*
D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1; D014357:Trypsin