Substrate- and effector-induced conformational changes in phosphofructokinase from white muscle of rainbow trout (Oncorhynchus mykiss): a fluorescence study.
Results of activity and spectral studies using fluorescence show that AMP and fructose 2,6-bisphosphate (F2,6P2) activate muscle phosphofructokinase (PFK) from rainbow trout (Oncorhynchus mykiss) through specific and similar conformational changes. Inorganic compounds, such as ammonium and phosphate ions, also increase enzyme activity allosterically; however, the structural alterations in the enzyme caused by these effectors are quite different from those caused by AMP and F2,6P2. No effects of the inorganic compounds on the environment of tryptophan residues of the enzyme were observed. Mg-ATP, a substrate of the enzyme, acts as an allosteric inhibitor at high concentrations. Although Mg-ATP and citrate inhibit the enzyme activity in a synergistic way, the conformational effects of these negative effectors are different. Mg-ATP caused a drastic decrease in fluorescence intensity of the enzyme, whereas citrate did not.
Su
J Y
JY
Institute of Biochemistry, Carleton University, Ottawa, ON, Canada.
Storey
K B
KB
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000494:Allosteric Regulation; D000818:Animals; D002951:Citrates / Q000494:pharmacology; D019343:Citric Acid; D004789:Enzyme Activation / Q000187:drug effects; D005635:Fructosediphosphates / Q000494:pharmacology; D009132:Muscles / Q000201:enzymology*; D017686:Oncorhynchus mykiss; D010710:Phosphates / Q000494:pharmacology; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors / Q000737:chemistry*; D011487:Protein Conformation; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D013050:Spectrometry, Fluorescence
D002951:Citrates; D005635:Fructosediphosphates; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D019343:Citric Acid; D000249:Adenosine Monophosphate; C027652:fructose 2,6-diphosphate; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1