30 



being tested followed by 0.03ml of enzyme. The reaction 



was initiated by adding 0.06ml of reaction mix containing 



3 3 



5- H-uridine triphosphate ( H-UTP) . After 10 minutes at 



37°C the reaction was stopped by addition of 0.1ml of 0.02M 



Na„P_0 7 with 2 . Omg/ml each of RNA and BSA and placed on ice. 



Ice cold TCA/Na P (7% TCA, 0.02M Na P ) was added(2.0ml/ 



tube) and the tubes allowed to stand on ice for 15 minutes. 



Precipitates were collected on GF/C glass fiber discs pre- 



washed with TCA/Na„P_0 7 on a vacuum manifold. Collected 



precipitates were washed three times with TCA/Na.P , three 



times with ethanol :ether (3:1), two times with ether, air 



dried at 80°C and counted in a toluene based scintillation 



cocktail . 



Estimation of the apparent inhibition constant for 



each inhibitor was performed determining the inhibition of 



3 



H-UTP incorporation obtained by a series of increasing con- 

 centrations of inhibitor for a constant quantity of enzyme 

 and a known concentration of labeled substrate ( H-UTP) . 

 The same assay was repeated with two or three different 

 concentrations of substrate. These results when plotted 

 according to the method of Dixon (Dixon and Webb, 1958) 

 yield a value for the apparent inhibition constant, K^. 

 Determination of Lectin-Associated Properties 



Binding to Sephadex . Ligand binding activity of the 

 conjugates was examined on the basis of their interaction 

 with Sephadex G-75. Preparations of conjugates were equili- 

 brated with 0.15M PBS , pH 7.0 by dialysis and applied to a 



