Y-GLUTAMYL PEPTIDES IN PLANTS 55 
y-L-Glutamyl-S-methyl-L-cysteine sulfoxide. This was reported to be present in Lima 
bean seeds? on the basis of cochromatography. It is possible that this may have been 
formed from y-glutamyl-S-methylcysteine during purification. 
y-Glutamylleucine. This substance was purified by chromatography on a cation ex- 
change resin and on cellulose powder from an extract of Lima bean seeds?. The structure 
was established by the chromatographic identification of glutamic acid and leucine 
among the hydrolysis products. By the formation of a DNP derivative, glutamic acid 
was shown to be N-terminal. By cochromatography and lability to acid, this peptide 
was tentatively identified in seeds of California small white beans, pinto beans, Blackeye 
beans and kidney beans. 
y-L-Glutamyl-b-aminotsobutyric acid. This was isolated in crystalline form from a 
50% alcohol extract of dormant bulbs of Wedgewood iris (Jris tingitana)* by chro- 
matography on an anion exchange resin with dilute acetic acid. Hydrolytic products 
were identical with L-glutamic acid and /-aminoisobutyric acid by cochromatography 
and infrared spectra. The elemental analyses of peptide and hydrolytic products 
agreed with theory. Glutamic acid was shown to be N-terminal by DNP derivative 
and the y-linkage was proven by the reaction with nitrous acid. 
y-L-Glutamyl-p-alanine. Pure crystalline material was obtained from the mother 
liquor left from the crystallization of y-glutamyl-f-aminoisobutyric acid. Only L- 
glutamic acid and /-alanine were obtained from hydrolysis of the crystals. Synthetic 
y-glutamyl-f-alanine gave an identical infrared spectrum to that of the isolated 
substance’. 
y-L-Glutamyl-L-tyrosine. This was isolated in crystalline form from the non-protein 
fraction of soy bean seed (Glycine max) by similar techniques as those used in puri- 
fication of y-glutamyl-6-aminoisobutyric acid. The proof of structure was obtained 
by elemental analysis, degradation, synthesis and infrared spectra of peptide and 
degradation products as in the case of y-glutamyl-f-alanine®. 
y-L-Glutamyl-L-phenylalanine. An acid labile substance has been isolated in crystalline 
form from onion bulbs (Allium cepa)® and soy bean seeds’. The hydrolytic products 
proved to be L-glutamic acid and L-phenylalanine by chromatography and elemental 
analysis. The y-glutamyl linkage was proven by decarboxylation with ninhydrin and 
reaction with fluorodinitrobenzene. Synthetic y-L-glutamyl-L-phenylalanine was iden- 
tical with isolated material’. 
y-L-Glutamyl-S-(f-carboxy-N-propyl) cysteinylglycine. A tripeptide related to gluta- 
thione has been isolated from onion bulbs by VIRTANEN AND MATIKKALA?®. Hydrolysis 
of the isolated material yielded L-glutamic acid, glycine and a S-substituted cysteine. 
The latter compound had a similar infrared spectrum to that of S-(f-carboxyl-N- 
propyl)cysteine. By the reaction of 6-bromoisobutyric acid and glutathione in the 
presence of sodium hydroxide, a tripeptide which chromatographed like the sub- 
stance from onions was obtained. The infrared spectra of the two compounds were 
similar. 
References p. 64 
