36 F. C. STEWARD AND J. K. POLLARD 
another compound (labeled 200 on the chromatogram). When isolated, the compound 
designated 200 proved to be o-acetylhomoserine, and its constitution was confirmed 
by GROBBELAAR AND STEWARD. The relations of this substance to homoserine are 
shown in the formulae below: 
O 
R CH,OH oo tte. 
ct ce CH 
ener. Me, aoe 
baa bear door 
Homoserine o-Acetylhomoserine 
One may now recognize an array of compounds which substitute different groups 
“R” in what would otherwise be alanine. R is CH, in the familiar four-carbon acid 
a-aminobutyric acid and a variety of other groups give the known compounds, shown 
in Table IT. 
ABE 
SOME NATURALLY OCCURRING DERIVATIVES OF HOMOSERINE 
AND ASPARTIC ACID 




R The formula on the left illustrates the 
| basic four-carbon q-amino acid structure 
CH of this family of compounds. The in- 
| dicated modifications at the y-carbon 
CH—NH, produce the natural products listed. 
| 
COOH 
“R” equals Derwative 
—CH, a-Aminobutyric acid 
—CH,OH Homoserine 
—CHO Aspartic, $-Semialdehyde 
—COOH Aspartic acid 
—CH,NH, a, y-Diaminobutyric acid 
—CH,—O—Ac o-Acetylhomoserine 
—CH,—_O—NH, Canaline 
—CH,—O—NH—C—NH, Canavanine 
| 
NH 
CE 
HC NE 
CH Azetidine-2-carboxylic Acid 
| 
COOH 
In a species of Kalanchoe (K. daigremontiana) compounds were seen on chromato- 
grams (Nos. 75 and 78 on Figs. 12 A and B) which proved to be two forms of the same 
substance because, when isolated from columns, the same substance was obtained in 
two fractions of the eluate. It subsequently transpired that these substances were 
References p. 42 
