PHYSIOLOGICAL STUDIES ON CEREALS. III. THE OC¬ 
CURRENCE OF POLYPEPTIDES AND AMINO ACIDS IN 
THE UNGERMINATED MAIZE KERNEL 1 
By S. L. Jodidi 2 
Organic Chemist, Office of Plant Physiological and Fermentation Investigations 
with the Cooperation of the Office of Cereal Investigations, Bureau of Plant Indus¬ 
try, United States Department of Agriculture 
INTRODUCTION 
Up to comparatively recent years 
the generally accepted idea was that 
the ungerminated kernel of cereals 
contains the nitrogen practically only 
in the form of proteins and nucleo- 
proteins. Having shown in previous 
papers that the ungerminated kernel 
of wheat (Triticum vulgare) (8) 3 and 
of oats (Avena sativa) ( 9) contains in 
addition to proteins also polypeptides 
and free amino acids, it was of consid¬ 
erable interest to find out whether or 
not this holds good for the maize kernel 
also. This work was prompted not 
only by the fact that corn (Zea mays) 
is the most important crop in the 
United States both in acreage and in 
value (11), but also by the consider¬ 
ation that few polypeptides have ever 
been shown to occur in plant and ani¬ 
mal materials and by the further con¬ 
sideration that the nutritive and physi¬ 
ological significance of foodstuffs and 
feedstuffs will not be fully understood 
until all their constituents have been 
determined. It is, therefore, believed 
that this paper fills a gap in our 
knowledge concerning the nitrogen 
compounds met with in the maize 
kernel. 
So far as proteins are concerned, 
Chittenden and Osborne (2) found 
that the corn kernel contains albu¬ 
mins, globulins, an alcohol-soluble 
protein (zein), and proteose. The lat¬ 
ter, which is found in the extracts of 
corn meal, may, however, be an artifi¬ 
cial product formed by hydrolysis of 
the above-mentioned proteins. In ad¬ 
dition to these proteins, the presence in 
the maize kernel of glutelin (a protein 
soluble in dilute alkalis or acids) was 
later reported by Osborne (12). Ac¬ 
cording to Osborne and Clapp (IS), the 
proportions in which the proteins oc¬ 
curred in yellow corn meal were as 
follows: Globulins, albumins, and pro¬ 
teoses, 0.45 per cent; zein (soluble in 
alcohol), 5 per cent; and glutelin 
(soluble in alkaline or acid solutions), 
3.15 per cent. Similar data have been 
reported by Johns, Finks, and Paul (10). 
Knowledge is very meager concern¬ 
ing the nonproteins, to say nothing of 
the complete absence of data with re¬ 
gard to their presence in the different 
varieties of corn. Owing to the work 
of Schulze and Castoro (15) it is known 
that the seed of maize contains 0.90 
per cent of nonproteins calculated on 
the basis of the oven-dried seed, or 4.9 
per cent if calculated on the total nitro¬ 
gen content. It is also known from 
the work of Schulze (14) that maize 
seed contain 0.25 per cent of lecithin. 
According to Czapek (8, p. 157), the 
proportion of lecithin in the yellow 
maize seed is 0.25 per cent, while in 
the white seed it is 0.28 per cent, calcu¬ 
lated on the oven-dried seed. In this 
paper it is shown that the ungerminated 
corn kernel contains amino acids and 
polypeptides. While it is true that the 
proportions in which they occur in 
the corn kernel are small, they seem 
nevertheless to be of considerable sig¬ 
nificance because amino acids are the 
bricks out of which the great protein 
structures are built, and for the further 
reason that the amino acids, being the 
most reactive material of the cells, are 
capable of performing important vital 
functions in the plant and animal or¬ 
ganism (1, p. 61-62). The polypep¬ 
tides, too, standing closely to the pro¬ 
teins, no doubt offer the immediate 
material for the synthesis of proteins. 
While the maize seed contains great 
quantities of proteins, the latter are 
not diffusible. On the other hand, the 
amino acids, being soluble and diffusi¬ 
ble, represent the best materialJ[for 
translocation of the nitrogen to the 
growing parts of the young seedling, 
before the proteolytic enzymes in the 
seed have come into play. 
1 Received for publication June 29, 1924; issued June, 1925. 
2 The writer’s thanks are due to J. G. Wangler, junior chemist, for assistance in carrying out the routine 
work. 
3 Reference is made by number (italic) to “Literature*cited,” p. 592. 
Journal of Agricultural Research, 
Washington, D. C. 
( 587 ) 
Vol. XXX, No. 6. 
Mar. 15, 1925. 
Key No. G-484. 
