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CHAPTER V 

 PROPERTIES OF THE S- PROTEINS 



The main focus in my studies of the properties of the 

 two bifunctional proteins was to detect possible 

 differential properties which might suggest that these 

 proteins are isoenzymes. Molecular mass, pH and temperature 

 optima, thermal inactivation, and Km values for both 

 functional domains of the bifunctional proteins, SP-I and 

 SP-II, have been determined. Effects on activity of each 

 protein by various compounds, including PCMB, were also 

 studied. 



RESULTS 



Activity peaks on a Celite column 



A Celite 545 column resolved about 6 peaks of SDH 

 activity when a more shallow gradient of ammonium sulfate 

 was applied than that used during the separation of the S- 

 proteins. Chapter IV (Fig. 5-1) . Dehydroquinase activity 

 was coincident with SDH activities. Fractions of the six 

 peaks containing the enzyme activities were pooled 

 separately, avoiding overlapping fractions as much as 

 possible, and were labeled as shown in Fig. 5-1. The six 



