Fluorescence study of ligand binding to potato tuber pyrophosphate-dependent phosphofructokinase: evidence for competitive binding between fructose-1,6-bisphosphate and fructose-2,6-bisphosphate.

摘要: The intrinsic fluorescence of potato tuber pyrophosphate:fructose-6-phosphate 1-phosphotransferase (PFP) was used as an indicator conformational changes due to ligand binding. Binding the substrates and allosteric activator fructose-2,6-bisphosphate quantitatively compared their respective kinetic effects on enzymatic activity. PFP exhibited a relatively high affinity for its isolated substrates, relative enzyme's K(m) (substrate) values. There are two distinct types fructose-1,6-bisphosphate interaction with PFP, corresponding catalytic activatory Activatory binding shares several characteristics binding, indicating that both ligands compete same site. Activation by or exerted primarily forward (glycolytic) reaction greatly increasing fructose-6-phosphate. effectors properties were markedly influenced assay pH. Results indicate increased glycolytic role during cytosolic acidification accompanies anoxia stress.