title: Thermodynamic properties of nucleotide-free EF-Tu from Thermus thermophilus in the presence of low-molecular weight effectors of its GTPase activity.
abstract: The thermal transition of elongation factor EF-Tu from Thermus thermophilus in the presence of low-molecular weight effectors was studied by differential scanning calorimetry. The effectors of GTPase activity used were the antibiotic kirromycin and the cations Li(+), Na(+), K(+) and NH(4)(+) in the chloride form. The temperature of thermal denaturation and the cooperativity of the transition of nucleotide-free EF-Tu (EF-Tu(f)) in the presence of kirromycin are comparable with those of the EF-Tu x guanosine-5'-[beta,gamma-imido]triphosphate (GppNHp) form, indicating similar conformational states. Increased concentrations of Na(+) and K(+) stabilized EF-Tu(f) in a manner similar to GppNHp. NH(4)(+) decreased the transition temperature of EF-Tu(f) and Li(+) decreased both the temperature and the calorimetric enthalpy of the thermal transition of EF-Tu(f). In the presence of salts, binding of kirromycin had a stabilizing effect on EF-Tu(f). Correlation between the GTPase activity and thermodynamic characteristics of EF-Tu(f) induced by kirromycin in the absence or presence of the cations is discussed.
authors: Department of Biochemistry, Faculty of Science, P.J. Safárik University, Kosice, Slovakia. sedlak_er@saske.sk
authors: Erik
authors: E
authors: Sedlák
authors: Gabriel
authors: G
authors: Zoldák
authors: Marián
authors: M
authors: Antalík
authors: Mathias
authors: M
authors: Sprinzl
mesh_terms: D000643:Ammonium Chloride; D002152:Calorimetry, Differential Scanning; D020558:GTP Phosphohydrolases / Q000096:biosynthesis / Q000737:chemistry*; D006165:Guanylyl Imidodiphosphate / Q000737:chemistry; D018021:Lithium Chloride; D008958:Models, Molecular; D010444:Peptide Elongation Factor Tu / Q000737:chemistry*; D011189:Potassium Chloride; D011728:Pyridones; D012965:Sodium Chloride; D013816:Thermodynamics; D016963:Thermus thermophilus / Q000737:chemistry / Q000378:metabolism*
chemical_list: D011728:Pyridones; D000643:Ammonium Chloride; D006165:Guanylyl Imidodiphosphate; D012965:Sodium Chloride; D011189:Potassium Chloride; D020558:GTP Phosphohydrolases; D010444:Peptide Elongation Factor Tu; D018021:Lithium Chloride; C008536:mocimycin