METABOLISM OF PEPTIDES IN DROSOPHILA 30S I¢ 
valine, radioactive valine was recovered as were other radioactive components. The 
ninhydrin pattern of the hydrolyzed material was complex and it is certain that 
amino acids in bound form were present prior to hydrolysis. As was the case with 
leucine, radioactive components other than the origin peak increase very rapidly 
initially and then show a much reduced rate of increase during the rest of the series. 
Attempts were made to alter the incorporation patterns found following injection 
of radioactive amino acids by using compounds which had been found to act as in- 
hibitors of protein synthesis in other systems*:®. Among a number of substances tested 
Ud) 
Glutamic 
acid 



Qi 
Oo 
Counts/min 
ine) 
Ol 
Time (min) 
Fig. 4. Larvae were injected with either chromatographic component A or B from Fraction 1 or 
with known glutamic acid. All three of the injected materials had an approximate specific activity 
of 70 ooo counts/min/ymole of glutamic acid present. Protein samples were obtained from injected 
larvae by homogenizing the animals in hot 80% ethanol. The insoluble material from this homo- 
genization was defatted and washed. It was then extracted with 0.1 N NaOH. Trichloroacetic acid 
insoluble material was then separated from the NaOH extract and following an additional washing 
radioactivity was determined and protein was assayed by the method of Lowry et al.® 
were chloramphenicol and f-fluorophenylalanine. Neither of these compounds nor 
any of the others tested was effective in altering the incorporation pattern, nor did 
they reduce radioactivity incorporated into protein extracts. Potential inhibitors 
were injected both prior to and simultaneously with the [C] amino acid being tested. 
Reinjection of isolated fractions. While a primary aim of the investigation on the low 
molecular-weight amino acid-containing compounds of Dyosop/ila has been to deter- 
mine their possible implication in protein synthesis, the complexity of the system has 
made this problem difficult. The results of one set of experiments in which partially 
purified fractions obtained from larvae injected with [4C| glutamic acid are given here. 
The chromatographic components A and B were obtained from Fraction 1 of the 
extraction procedure given in the preceding paper. A and B were then separated from 
the bulk of the Fraction-1 material by chromatography with propanol—water (3 : I). 
Component A moves to the same chromatographic R as glutamic acid does in the 
solvent used. On hydrolysis A gave three spots, probably glycine and lysine in addi- 
tion to glutamic acid, on the basis of chromatographic behavior. The glutamic acid 
References p. 155 
