COMPOSITION OF MICROBIAL AMINO ACID POOLS 89 
AND EssER observed 41 peptides most of which contained a large number of amino acid 
residues. Acidic peptides predominated and were more heavily labeled. McManus"! 
also has observed the occurrence and formation of peptides in 7. wtilis. On the other 
hand, CowlE AND WALTON* failed to detect peptides in trichloroacetic acid extracts 
of Torulopsis utilis following exposure of cells to “C-fructose. 
Dialyzed ethanolic extracts from Ps. hydrophila were found to contain 43 peptide 
fractions, 36 of which were examined for constituent amino acids. At least five amino 
acids were found in all fractions after hydrolysis and most contained eight or nine 
amino acids. Although basic peptides were usually detected, except for histidine, in- 
corporation of isotope during 2 h incubation occurred only in the neutral and acidic 
fractions. These authors estimated that approx. 6 mg/g dry weight of free amino 
acids occur in this organism (approx. 4 wmoles/too mg) and that an additional 3 mg/g 
of peptides occur. This is a significant amount of material, particularly if the generali- 
zation is substantiated by further study that gram-negative bacteria contain relatively 
small pools. 
TuRBA AND Esser suggest a relation of these peptides to the synthesis of protein. 
CONNELL AND Watson adopted a more cautious view towards the significance of 
their results, and point out that one third of the peptide fractions analyzed contain 
diaminopimelic acid, suggesting a relation of such peptides to cell wall biosynthesis. 
It is clear that the detection of large and varied peptide pools so far has been the 
exceptional finding. The more common experience has been the detection of one or a few 
unknown spots on chromatograms which disappear when extracts are heated with strong 
acids. In a number of instances, some of them listed in Table X, more definitive evi- 
dence for the presence of peptides has been reported. Sorm and his coworkers have 
isolated two peptides from F. coli and identified them as glutamylalanine and glu- 
tamyl-y-aminobutyric acid. These substances are found only in small amounts in the 
normal strain used. They are present in much larger amounts in a chloramphenicol- 
resistant strain and in the normal strain grown with this antibiotic. More recently 
TABLE X 
REPORTS OF PEPTIDES IN MICROBIAL EXTRACTS 

Number of Ref. 
Organism : omposition 
7 peptides Composit numbers 
Pseud. hydrophila 43 Most protein amino acids and DAPA 
E. colt 2 Glutamylalanine 7a 
Glutamyl-y-aminobutyric acid 
E. cola 30 10 amino acids; most often glu, cyst, gly 65 
Pseud. saccharophila I Thre, gly, 2 unknowns 118 
Staph. aureus I Glu, lys, ala, gly 71 
Strep. faecalis I pD-alanyl-p-alanine 89 
Mycobact. tuberculosis I Asp, leu, met/val, ser, gly, cyst, glu, ala, 141 
unknown 
Coryn. diphtheriae I Ala, gly, lys or arg, glu, DAPA 189 
Torula utilis 41 Most protein amino acids 184 
Torula utilis 2 Glu, gly, ala, leu, phe I21 
Torulospis utilis I Citr, (orn?), glu, cyst, gly 123 
Pen. chrysogenum I 0-(a-aminoadipyl)cysteinylvaline 6 

References p. 105/108 
