Sulphate activates phosphorylase b by binding to the Ser (P) site.
The notion, in a recent crystallographic study on the R state phosphorylase b (Barford, D. and Johnson, L.N. (1989) Nature 340, 609-616), that sulphate ions activate the enzyme by interacting within 2 A of the phosphorylatable Ser-14, is directly supported by kinetic studies on phosphorylase b', a proteolytic species which lacks the N-terminal 16 residues. The results show that this form of the enzyme is no longer activated by ammonium sulphate.
Leonidas
D D
DD
Biological Research Center, National Hellenic Research Foundation, Athens, Greece.
Oikonomakos
N G
NG
Papageorgiou
A C
AC
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000495:Allosteric Site; D000645:Ammonium Sulfate / Q000494:pharmacology; D001665:Binding Sites; D004789:Enzyme Activation; D007700:Kinetics; D010763:Phosphorylase b / Q000378:metabolism*; D011487:Protein Conformation; D012694:Serine; D013431:Sulfates / Q000494:pharmacology*
D013431:Sulfates; D000249:Adenosine Monophosphate; D012694:Serine; D010763:Phosphorylase b; D000645:Ammonium Sulfate