SOLUBLE, NITROGENOUS CONSTITUENTS OF PLANTS 35 
stituents which include the y-methyleneglutamyl compounds; the latter are probably 
derived by loss of water from y-hydroxy-y-methylglutamic acid. 
Obviously a metabolite which occurs in such diverse plants as a fern (Adiantum) 
and a flowering plant (Tulipa) must play a somewhat general role. In fact, it 1s sur- 
prising how widespread the distribution is of some compounds that owed their discovery 
to chromatography.A survey of the Lihaceae permitted one to show how frequently such 
compounds as those listed in Table I occurred in the species and genera of this family ; 
and, as the figures show, these compounds are of such wide distribution that they 
may be regarded as general metabolites which happen to accumulate in detectable 
amounts in certain plants or organs or under certain genetic or nutritional conditions. 
Despite this, however, the Liliaceae revealed a baffling number of distinct ninhydrin- 
reacting compounds of which 45 were recognized in the 88 plants of this family that 
were examined!?3. 
The long list of new, or recently discovered, natural nitrogen compounds cannot be 
fully mentioned here. It has been reviewed on a number of occasions (cf. refs. 14, 29). 
It includes new hydroxyamino acids (y-hydroxyvaline and homoserine), an o-acetyl 
derivative as of homoserine; new sulphur compounds (for summary see ref. 12) and 
several new derivatives of glutamine (cf. ref. 28), some of which are as yet only partially 
identified (cf. the contribution of THoMPSON to this symposium). 
Some hydroxy amino acids and their derivatives 
On a phenol-butanol-acetic acid chromatogram (Fig. 11 from a chromatogram made 
by GROBBELAAR") of the shoot of Piswm, homoserine can be clearly seen and also 
PrSUmM SATIVUM = ALC. SOL. N COmPOS. OF SHOOT 
LEUCINE 
ae VALINE 
¥i- AMINOBUTYRIC . 
% 
ALANINE 
200 
R  OTHREONINE GLUTAWIC 
GLYCINE 

ASPARTIC 
2 
= ACETIC ——»> 

HOMOSERINE 
SERINE 
ee ay 
a ASPARAGINE <e 
ARGININE uysine oe 4— PHENOL 
BUTANOL 
Fig. 11. The ninhydrin-reactive, alcohol-soluble compounds of the pea (Pisum sativum L.). Note: 
The occurrence of homoserine and of another unidentified substance (No. 200) now known to be 
o-acetylhomoserine. 
References p. 42 
