AMINO ACID INCORPORATION BY LIVER MICROSOMES 



TABLE IV 



227 



Incorporation of P*C]-l-leucine into Protein by Cell- Free Preparations 

 FROM Unfertilized and Fertilized Psammechinus Eggs 



Preparation of cell fractions essentially as in Fig. i. The incubation system 

 contained 0-4 ml. of whole homogenate or o-6 ml. of 12 000 g supernatant fraction 

 from equal egg samples in combination with o-6 ml. of rat liver cell sap [5], or 

 RNP-particles from 0-7 ml. of packed eggs in combination with 0-65 ml. of the 

 liver cell sap. System otherwise as in Fig. i. Incubation period (20 ) 30 min. 



that this effect persisted also in preparations from disrupted cells. However, 

 with RNP-particles isolated from the homogenates by the detergent 

 treatment and layering procedure briefly mentioned in a previous section 

 this fertilization effect was less marked. 



100 



80 



60 



E 

 d. 

 o 



AG' 



20 



20 40 60 



Period otpreincubation.minutas 



Fig. 3. Incorporation activity of a mitochondria-free rat liver homogenate at 

 different periods of incubation (20"). At the periods indicated o-o8 ^tmole [^'*C]- 

 L-leucine, 10 /xmoles PEP, 15 /xg. pyruvate kinase, i /xmole ATP and 02 /xmole 

 GTP were added. Incubation period after these additions 5 min. 



