742 DYNAMIC ASPECTS —- AMINO ACID POOL TURNOVER 
BIOCHEMICAL PRODUCTION OF LIPO-AMINO ACID COMPOUNDS 
BERNARD AXELROD, JOSEPH L. HAINING anp TOSHIO FUKUI 
Department of Biochemistry, Purdue University, Lafayette, Ind. (U.S.A.) 
To begin with we must say that our interest in the problem of lipo—amino acid 
compounds was stimulated by a provocative suggestion by HENDLER that lipo- 
amino complexes might be concerned with the biological synthesis of proteins. His 
suggestion was based mainly on his observations that an incorporation of labeled 
amino acid into lipoidal material occurred in incubating minced hen oviduct and 
400 


Ww 
2) 
O 
Counts / min/mg 
Protein 
© 
15 SORe45 160 80 120 150 
Time (min) 
Fig. 1. Time course of the incorporation of {!4C]phenylalanine into protein and lipid fractions of 
a rat-liver microsome preparation. Each vessel contained 0.7 ml of whole supernatant solution, 
1ymole of ATP, toymoles of 3-phosphoglyceric acid, 0.23 wmole of pDL-[3-!4C]phenylalanine 
(500 000 counts/min), and water to a final volume of 1 ml. After incubation at 37° under N,-CO, 
(95 : 5) the reaction was stopped by adding trichloroacetic acid to the vessels and the protein 
and lipid fractions prepared from the precipitated material. (By courtesy of the J. Biol. Chem.) 
that the relative rates of labeling of protein and of lipoidal substance was not in- 
consistent with this view!. At that time, meeting with frustrations on another 
aspect of protein synthesis, and having a goodly supply of rats on hand we attempted 
to see if this phenomenon occurred in rat—liver preparation, and if it did, how it 
compared with “conventional” incorporation into protein. 
AMINO ACID INCORPORATION INTO PROTEINS AND LIPIDS 
BY CELL-FREE PREPARATIONS OF RAT LIVER 
The supernatant obtained by centrifuging a homogenate of rat liver at 10 000 x g, 
is so easily prepared and so frequently shown to be suitable for showing amino acid 
incorporation into protein, that we confined our attention to this system. Using the 
References p. 749 
