go J. T. HOLDEN 
this group has reported the occurrence in E. coli of 30 unknown substances which 
release a variety of amino acids on acid hydrolysis®. The unknown substance reported 
by Hancock to occur in extracts of S. aureus was shown by hydrolysis of isolated 
material to contain glutamic acid, lysine, alanine and glycine. This composition corre- 
sponds closely to the major amino acids found in cell walls of this organism suggesting 
a metabolic relation between the two. The material isolated by IkAWA AND SNELL 
from S. faecalis*® also seems to be an intermediate in the synthesis of the mucopeptide 
portion of the cell wall. 
In her early study on the amino acid pool of Corynebacterium!§§ Work detected 
two unknown ninhydrin-positive substances. One of these subsequently was shown 
to be diaminopimelic acid. The other appeared to be a relatively stable peptide which 
on hydrolysis with strong acid or base released varying amounts of alanine, glycine, 
lysine (or arginine), glutamic acid and diaminopimelic acid. In retrospect, it is very 
likely that this material also has a close relation to cell wall metabolism. An amino- 
adipyl peptide, reported by ARNSTEIN ef al.®» ® to occur in Pen. chrysogenum along 
with free aminoadipic acid, may be involved in the biosynthesis of penicillin by this 
organism. 
In addition to the substances cited here a large number of antibiotic peptides have 
been isolated from microbial cultures. The earlier literature has been summarized by 
SyNGE?”? and references to the more recent reports can be found in current volumes 
of the Annual Review of Biochemistry (e.g., ref. 158). It should be noted that in most 
instances these substances are isolated from culture filtrates. 
Nucleotide-peptides. The occurrence in bacteria of uridine-muramate-peptides and 
their involvement as intermediates in cell wall biosynthesis has been reviewed exten- 
sively®7; 4,176 and, therefore, will not be considered further here. Recently, a consider- 
able number of nucleotide-peptides have been isolated from yeast and Chlorella which, 
by virtue of their occurrence in these organisms, would appear to have no relation 
to cell wall biosynthesis. The most prevalent suggestion of a metabolic function for 
these substances is an involvement in protein synthesis. In most of these compounds 
the peptide is linked to uridine and usually yields an hydroxamate on treatment with 
hydroxylamine. 
KONINGSBERGER et al. originally detected such compounds in extracts of quick- 
frozen yeast. Subsequent reports from various laboratories substantiated the natural 
occurrence of these substances. GILBERT AND YEMM®, for example, isolated a uridine- 
containing fraction from ethanol extracts of exponentially growing Torulopsis utilis 
which on hydrolysis yielded aspartic and glutamic acids, arginine and alanine. In an 
extensive study‘; 44, 75, 76, 77 Harris et al. have detected a variety of compounds in 
Saccharomyces cerevisiae. In one instance a compound was isolated which on alkaline 
hydrolysis yielded UMP and a tetrapeptide containing two units each of alanine and 
arginine 76, A sizeable number of other amino acids have been shown to occur in such 
compounds, in many cases in peptidic form and linked to 5’-uridylic acid as well as 
to 5’-adenylic acid. This group has presented kinetic evidence supporting the proposal 
that the nucleotide-peptides are intermediates of protein synthesis’. 
HaAse et al. also have reported extensively on nucleotide-peptides in yeast and 
Chlorella**-*!, and for the latter organism have suggested that they participate in 
reactions associated with nuclear and cell division. In these studies, ultraviolet- 
References p. 105/108 
