Scientia Sinica

No. 1 WANG, TSOU, & WANG: STUDIES ON SUCCINIC DEHYDROGENASE I 85

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mperature on the activity of succinic dehydrogenase. Reaction carried out as described in the section on methods. The logarithm values of the optical-density changes in 10 min. are plotted against the reciprocals of absolute temperatures. The upper curve is for the enzyme previously activated by incubation with succinate for 5 days at 0°C under vacuum and the lower curve is for the enzyme without succinate activation,

Fig, 7. Effect of te

critical temperatures of transition from one value of activation energy to another tend to be lower. The activation energy values obtained from the graphs are summarized in Table 8.

ues for the Succinic Dehydrogenase-catalyzed Oxidation of

Table 8. Activation Energy Val Succinate by Ferricyanide,

Temperature Range, °C

Activation Energy, cal. : : Before os with After Incubation with Succinate uccinate 10200 o—15 o0—10 5800 15—30 10—23 2380 30—38 23—38

Some PRELIMINARY OBSERVATIONS ON THE PROSTHETIC

Group OF THE ENZYME

Colour and absorption spectra of purified enzyme. The highly purified enzyme solution is perfectly clear and 1s strongly amber coloured. Fig. 8 shows