II. PLANTS 
THE SOLUBLE, NITROGENOUS CONSTITUENTS 
OF PEANES 
F. C. STEWARD anp J. K. POLLARD 
Department of Botany, Cornell University, Ithaca, N.Y. (U.S.A.) 
This account relates to developments, made since the first use of amino acid chromatog- 
raphy, largely from one laboratory; in this way, certain trends may be emphasized. 
However, reference may and should be made to other more complete reviews (¢.g., 
STEWARD AND THOMPSON®9; STEWARD, ZACHARIUS AND POLLARD®?; STEWARD AND 
POLLARD2?; GREENSTEIN AND WrniItTz!*) for fuller citations and for more complete 
reference to the contributions from other laboratories than can here be given. Reference 
may also be made to the volume on nitrogen metabolism, subedited by MoTHES?®*. 
In view of the importance of what plants do with nitrogen, the incomplete know- 
ledge and often ingenuous interpretation of nitrogen metabolism, even in recent 
times, has been surprising. The discovery of asparagine (1806) and later of glutamine 
(x883) focused attention upon these amides, which with arginine (especially in 
conifers) accumulate as nitrogen-rich storage or mobile substances (see CHIBNALL® 
for historical citations). The views of PFEFFER, SCHULZE, and later PRIANISHNIKOW 
gave to ammonia and the amides an important place in sequences of protein synthesis 
and breakdown and recognized that these nitrogen-rich compounds, with organic acids 
derived from sugar as the carbon skeletons, represented the organic starting material 
for protein metabolism. It was, however, through the work and writings of VIRTANEN, 
CHIBNALL, and Vickery that the keto acids, which are salient intermediates or 
the Krebs cycle, first appeared as the principal “ports of entry” for nitrogen into 
organic combinations; in this way the gap between carbohydrate and nitrogen metab- 
olism was bridged. ScHuLZE and PRIANISCHNIKOW spent much of their respective 
careers in the attempt to detect the free occurrence of the amino acids which are 
necessary to build protein, and they believed them to be formed from ammonia which 
PRIANISCHNIKOW termed the a and w of nitrogen metabolism. However, the discovery 
of group transfer reactions upheld the amino acids alanine (from pyruvic acid), 
aspartic acid (from oxaloacetic acid) and glutamic acid (from a-ketoglutaric acid) as 
the main starting points, the “Grundaminosiduren” of VIRTANEN, for nitrogen metab- 
olism. 
Despite the combined activities of SCHULZE and PRIANISCHNIKOw, they listed in 
1906 only ten amino acids as capable of occurring free in plants and even these had 
been demonstrated usually singly in selected situations. This list (arginine, histidine, 
isoleucine, leucine, lysine, phenylalanine, proline, tryptophane, tyrosine and valine), 
strangely, did not contain aspartic and glutamic acids, for they were then regarded 
when found free as apt to be decomposition products of the generally occurring amides. 
Thus early attention was focused on the detection in plants of those free amino acids 
which are protein building blocks and, apart from work directed to the recognition 
of many of the nitrogen bases and intermediates of alkaloid synthesis, surprisingly 
References p. 42 
