286
MAURICE WELSCH
cates the possible occurrence of moieties unrelated to amino acids, such
as thiazole fragments (LV), sugars (streptothricin group), and fatty
acids (172e).
HO— S- CH 2 ~CHNH 2 — COOH
II
ο
Cysteic acid
(LI)
COOH
Pipecolic acid
(LII)
Ν
(
„COH— COOH
I
CH 2 NH 2
H 2 N
^N'
Η
Geamine
(Lin)
η
CHNH 2 —CH 2 —COOH
0-(2-Thiazole)-/3-alanine
(LIV)
HOOA
CH 3
I
3
CHNHP— CH—CH,
2-(l-Amino-2-methylpropyl)thiazole-4-carboxylic acid
(LV)
The latter type of compound assumes a greater importance in some
microbial metabolites. Thus DL-fumarylylalanine is a metabolic product
of Penicillium resticulosum; 3-oxydecanoic acid is bound to serine in
L-Dab—*"D-Leu—^-L-Dab—*- L-Leu
"
f
la
L-Dab-— L-Dab-— L-Threo-— L-Dab
a
a
jy
MeOct
(according to Kurihara and Suzuki)
MeOc t —2-Dab —D-Leu—L-Leu —Dab
L-Threo-—L-Threo
Dab
t
|«
\y
Dab
Dab
or
Dab
Dab
L-Threo
Dab
Μ
»
»
Dab
Dab-*- L-Threo
a |
a
Dab——L-Leu-— D-Leu-*—Dab— MeOct
a.
a.
(according to Dautrevaux and Biserte)
Proposed structures for Colistin
(LVI)