AMINO ACIDS AND DERIVATIVES IN DROSOPHILA 137 
plus boiling-water extract was fractionated with variations in the elution system in 
the first four. Details of extraction and elution systems are given in the figure and 
analytical methods are the same as described later. The data are given as wmoles/m| 
(15-ml fractions) with the white portion on the graph showing ninhydrin equivalents 
before hydrolysis and the black bars the total amounts after acid hydrolysis. Positions 
and breadth of bands (for go°%, recovery) from fractionation of known amino acids 
in the same system are indicated by the abbreviations and arrows above the graph. 
This gives an index of the resolving power of the system since the total moles of amino 
acid exceeded that of the unhydrolyzed extract. 


fe) 
04 Gas 
/ fe) 
em 
xe O 
Oo Te 
= / 
% 
= 
— 
8 
S 
5 070 
s a fe) as 
3 yy ee 
Wf O 80 
Z—O 
Ql 
O (Oe 420 AGOGO) IS OMEnCO 
MINUTES 
Fig. 1. Instability of amino acid derivatives in larval homogenates. Homogenates of second instar 
larvae (made in four parts of water at —o°) were incubated at temperatures indicated. Samples 
were spotted directly on paper for chromatography and the spots were dried quickly by suction. 
Increases observed were general in all amino acid positions and largely at the expense of peptides 
rather than proteins. 
From these experiments and additional ones involving extensive paper chromatog- 
raphy and electrophoresis of each fraction we were able to conclude that the larval 
extracts contain significant quantities of at least 600 peptides and a considerable 
variety of other classes of amino acid derivatives. For example, essentially none of 
the material before fraction go represents free amino acids and nearly all of the material 
from fraction 280-306 represents fairly large mixed peptides. Predominantly acidic 
peptides come in the region o—go. Thus, it was clear from secondary fractionations 
that even most of the minor variations in the amounts of materials in the column 
fractions were significant. Furthermore, few, if any, fractions contained single pure 
substances and the necessity for development of more elaborate fractionation methods 
became evident. Before proceeding to these problems it is again worthy of note that 
an extract giving the results of Fig. 2 gives, by paper chromatography, a pattern 
interpretable as representing a mixture of some 20 amino acids plus five or six peptides. 
Obviously such an interpretation is incomplete. 
References p. 146 
