Studies of Manganous Nucleotide Complexes with Uridine Diphosphate-Glucose Pyrophosphorylase, Formyltetrahydrofolate Synthetase, and Creatine Kinase

摘要: Abstract The longitudinal proton magnetic relaxation rate (PRR) of water in manganous complexes has been measured as a function frequency. ternary ion, nucleotide, and enzyme for three enzymes namely, UDP-glucose pyrophosphorylase, formyl tetrahydrofolate synthetase, creatine kinase, all exhibited maximum the value between 8 25 MHz. This observation shows that correlation time which modulates dipolar interaction electron nuclear spins is frequency-dependent must therefore be ascribed to spin time. enhancement PRR relative Mn(II) aquo-ion arises because times (10-8 ∼10-9 sec) are much longer than rotational (∼3 x 10-11 simple aquo complex. modulation slower from no dominant macromolecular since their tumbling order 10-8 10-7 sec. In case abortive quaternary complex, E-Mn-ADP-creatine, deenhanced most markedly presence nitrate increases monotonically with decreasing number ligands first coordination sphere complex calculated its frequency dependence less one-half. rates obtained at various frequencies temperatures point involvement only outer It concluded conformational change occurred upon addition second substrate makes inaccessible solvent water. binding MnUTP pyrophosphorylase binary absence enzyme. behavior this nucleotidyl-transferring differs regard phosphoryl-transferring it inferred scheme may also differ.