SOME AMINO ACIDS FROM PLANTS 47 
demonstrated in a species of Pseudomonas, led to the production of pyrazole, ammonia 
and pyruvic acid (TAKESHITA, NISHIZUKA AND HAYAISHI?’); here again a ready 
analogy with tryptophan metabolism may be drawn for tryptophanase action yields 
indole, ammonia and pyruvic acid (HOPKINS AND COLE®’). 
p-Pyrazol-1-ylalanine has a slight ability to undergo transamination with a-keto- 
glutarate or pyruvate when disrupted mitochondria obtained from etiolated seedlings 
of Citrullus vulgaris or Cucumis melo were used as a source of transaminases (Table IT). 
TABLE II 
TRANSAMINATION BETWEEN AMINO ACIDS 
Shows the amounts of transamination occurring in 1 h at 37° between various amino 
acids and a-ketoglutarate or pyruvate when reactions were catalysed by extracts of 
mitochondria obtained from Citrullus vulgaris and Cucumis melo seedlings. Trans- 
amination is expressed as moles glutamate or alanine formed per ml of reaction 
mixture. Reaction mixtures contained the following amounts of substances per ml: 
a-ketoglutarate or pyruvate (adjusted to pH 7.4), 50 wmoles; L-amino acids, 50 
moles; potassium phosphates, pH 7.4, 50 wmoles. 

umoles glutamate formed pmoles alanine formed 

from «-ketoglutarate from pyruvate 
Amino acid donor —__—— ———_—— - —-—___ 
Citrullus Cucumis Citrullus 
vulgaris extract melo extract vulgaris extract 
p-Pyrazol-1-ylalanine 0.91 0.25 0.37 
Aspartic acid 6.7 4.2 2.4 
Alanine 8.6 gfe — 
Histidine 0.94 0.31 0.31 
y-Aminobutyric acid 0.41 0.32 0.39 

N*-Ethyl-L-asparagine and N*4-(2-hydroxyethyl)-L-asparagine. Extracts of certain 
species examined during the pyrazolylalanine investigations also contained compounds 
giving brown ninhydrin reacting spots on paper chromatograms. Two of these have 
now been characterized as N?-ethyl-L-asparagine (VIII) and N*4-(2-hydroxyethyl)- 
L-asparagine (IX). The former was isolated first from the green parts of Ecballium 
elatertum; yield about 1 g from 4.5 kg fresh material (GRAY AND FOWDEN?%). It has 
been obtained more recently in larger amount from shoots of Bryonia dioica (7.1 g 
from 20 kg plant material). During the latter isolation, 1.2 g of N4-(2-hydroxyethyl)- 
L-asparagine was obtained. The compounds responsible for the other brown spots on 
chromatograms of bryony extracts remain to be identified. However, it is apparent 
already that plants may contain a series of aspartic acid or asparagine derivatives 
that may be shown ultimately to be as extensive as the class of compounds now 
known to be based on glutamic acid or glutamine. 
Compounds VIII and IX were decomposed by acid hydrolysis; VIII gave an 
equimolar mixture of aspartic acid and ethylamine whilst IX yielded aspartic acid 
and ethanolamine. Both compounds were hydrolysed considerably more slowly than 
asparagine by 2 N HCl solutions at roo° and evidence obtained from paper chromato- 
grams suggested that intermediate compounds, possibly cyclized forms of VIII and 
IX, were present during the earlier part of the hydrolysis period. 
References p. 53 
