88 J. T. HOLDEN 
F. solani f. phaseoli?°; Hypomyces aurantius'®!; Mucor adventitius aurantiacus'8 ; 
Phycomyces nitens, Pythium ultimum, Stereum purpureum, Thamnidium elegans?" ; 
Ustilago zeae*®; Verticillium albo-atrum'; Zygorhynchus moelleri*8, 
Summary of quantitative studies 
Some of the quantitative data included in Tables I-VIII are collected in modified 
form in Table IX to show the relative amounts of different amino acid types found 
in the total pool. It should be recognized that only a limited number of quantitative 
studies are available and that these pools are highly variable. Nonetheless, an appraisal 
of these data suggests that some of the apparent relations may survive more intensive 
investigation. The poolin gram-positive bacteria, for example, appears to be dominated 
by the dicarboxylic amino acids. The yeasts also contain large quantities of glutamic 
and aspartic acids, and an additional significant portion of the pool is made up by 
their amides. The basic amino acids generally do not form a major part of the pool 
except in the yeasts where values on the order of 20°{ are encountered. The fungi, 
with the possible exception of the yeasts, appear to be consistently high in the neutral 
aliphatic amino acids. y-Aminobutyric acid and f-alanine form a significant part of the 
pool only in the molds and other fungi, although there are qualitative reports of their 
occurrence in bacteria (e.g., Fig. 7; ref. 83). Suggestive trends in some of the other 
groups can be seen, but there are too many exceptions to permit a formal statement. 
Occurrence of additional pool components 
Most of the substances observed in the studies summarized to this point are the amino 
acids generally found in protein and in the pools of plant and animal organisms. 
When the commonly employed extraction and chromatographic procedures are used, 
these amino acids clearly form the major part of the pool in most microorganisms. 
It must be recognized, however, that the influence of the cell disruption and analytical 
procedures used on the composition of the extracted pool has not been examined 
exhaustively. The experiments cited by MITCHELL AND Simmons (p. 136) show clearly 
that the relatively commonplace pools observed by many workers in Drosophila in 
fact may be found to contain many more components when other analytical proce- 
dures are used. 
It should be borne in mind also that no systematic effort has been made here to 
list all unusual amino acids or amino acid derivatives encountered in unautolyzed 
cell extracts. Rather, attention has been focused largely on investigations in which 
the total pool was examined. Many of these studies, however, have disclosed substances 
of unusual interest and some of these observations will be discussed below. 
Peptides. Impressive evidence for the occurrence of sizeable peptide pools in micro- 
organisms is found in the work of TURBA AND EsseEr!}83, 184 on Torula utilis and of 
CONNELL AND WATSON®®; 99 on the gram-negative bacterium Pseudomonas hydrophila. 
In both cases, cells were exposed to an isotopically labeled carbon source (acetate or 
glucose), harvested at intervals of a few second to a few hours, extracted with boiling 
ethanol and fractionated by paper electrophoresis into basic, neutral and acidic com- 
ponents each of which was fractionated further by paper chromatography. TURBA 
References p. 105/108 
