A NUCLEAR MAGNETIC-RELAXATION STUDY OF CONFORMATIONAL-CHANGES INDUCED BY SUBSTRATE AND TEMPERATURE IN BOVINE LIVER THIOSULFATE SULFURTRANSFERASE AND YEAST HEXOKINASE

Nuclear magnetic relaxation studies were performed on thiosulfate sulfurtransferase and hexokinase. Observation of proton spin-lattice relaxation times T1 indicates that structural transitions occur in these enzymes in the range 0-40.degree. C and that there are different temperature-dependent forms of thiosulfate sulfurtransferase and hexokinase. Thermal transitions between these forms are affected by the binding of the substrates. The results may be due to changes in the interactions between the structural domains into which the single polypeptide chains of thiosulfate sulfurtransferase and hexokinase are folded.