iS) 
bo 
M. WINITZ 
it will be recalled that VIRTANEN AND HIETALA, in their initial isolation of y-hydroxy- 
glutamic acid, obtained the material in amounts insufficient for optical rotation values 
to be taken. The answer as to the configurational identity of natural y-hydroxy- 
glutamic acid, as well as independent experimental verification of its existence in 
nature, was subsequently provided by an optical rotation determination of the natural 
material”, which was isolated by STEWARD AND POLLARD’ in several g yield from 
Phlox decussata seed and which was shown by them to possess a chromatographic 
behavior identical with that of an authentic sample of the synthetic allo form*® of the 
amino acid. An optical rotation determination of the natural material in water and 
4 N HCI revealed it to possess the same values, within the limits of experimental 
error, as that of the L-isomer, and hence sufficed to unequivocally establish its identity 
as allo-y-hydroxy-L-glutamic acid”. 
RECAPITULATION 
Thus, from the data presented, it becomes evident that the natural occurrence of 
allo-y-hydroxy-L-glutamic acid may be considered as established according to the 
criteria presented earlier. If these criteria seem unnecessarily rigid, it is well to remember 
that the analogous criteria, proposed some 30 years ago by VICKERY AND SCHMIDT’, 
were accompanied by the following admonition: “Although these criteria may appear 
somewhat arbitrary, they are essential, unless one is prepared to accept a host of 
preparations that have been described, from time to time, but for the exact nature 
of which convincing proof has not been presented. Too many errors have been com- 
mitted to warrant any but a thoroughly conservative attitude towards newly discovered 
amino acids.” They went on further to state: “Even the greatest leaders have made 
mistakes. FISCHER himself described diaminotrioxydodecanoic acid in 1904, but with- 
drew it in 1917.” The rapidly increasing numbers of naturally occurring amino acids 
that are currently being reported, all too often without adequate substantiation, make 
this admonition equally as cogent today. 
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. VICKERY AND C. L. A. Scumipt, Chem. Revs., 9 (1931) 169. 
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SHAS ScHMIDT, Ann. a tae 2 (1933) 7 
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12 J. P. GREENSTEIN AND M. WINITz, in Chemistry of the Amino Acids, J. Wiley and Sons, New 
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18 J. D. Ociz, M. A. LoGan anv R. B. ARLINGHAUS, Federation Proc., 20 (1961) I. 
14 L. BENOITON, M. Win11z, R. F. Corman, S. M. BiRNBAUM AND J. P. GREENSTEIN, J. Am. Chem. 
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18 C. E. DENT, Biochem. J., 43 (1948) 169. 
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oo sl & 
HAaNN 
