COMMUNICATIONS TO THE EDITOR
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VOl. 76
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ENZYME
i
. 0 9 I p M UDPG
/-
.8
THEOR. FOR 2 M. DPN+ R E D U C . / M , UDPG OXID.
.6
.4
.2
0
2
4
6
8
IO
12
14
16
30
M I N UTES. Fig. 1.-Reduction
of D P N + by purified UDPG dehydrogenase. Each cuvette contained 0.1 ilf diethanolarnine buffer, pH 9.0, 0.4 p M DPIi+, UDPG as indicated and enzyme in 1 cc.
column and eluted with an NaCl gradient in 0.01 N HC1. A zone in the region expected for UDPGA contained a UDP compound which gave carbazole color. For each mole of uridine (ultraviolet adsorption) 0.93 mole of glucuronic acid was present, based on the carbazole reaction. The enzymatic oxidation product of UDPG, even when generated in the presence of semicarbazide as an aldehyde trap, could be utilized to generate o-aminophenol glucuronide in the presence of washed microsomes and o-aminophenol (Table I). At least 75% of the generated UDPGA could be transferred to the acceptor. No evidence for the appearance of an intermediate compound a t the oxidation level of aldehyde has so far been obtained; attempts to accumulate such a compound are in progress.
THE PARTIAL SYNTHESIS OF TOMATIDINE'
Sir:
The steroid alkaloid toinatidine,2 derived by hydrolytic cleavage of the tetroside tomatine, native to certain species of Lycopersicuw, has been shown to yield as important degradation fragments AIfiallopregnen-3/3-ol-20-one3 and tigogenin l a c t o ~ i c . ~ These scission products, together with the secondary nature of the alkamine, diagnostic behavior under conditions of hydrogenation, and empirical composition C ~ ~ H ~ L have N O ~supported , the attribution of a skeletal formulation akin to that characteristic of solasodine, the structure of which has been confirmed by partial synthesis from kryptogenin5 and from diosgenh6 Inasmuch as it is now known7 that diosgenin and sarsasapogenin give rise, XATIONAL INSTITUTE OF ARTHRITIS JACK L. STROMINGER
METABOLIC DISEASES AND HERMAN M. KALCKAR~ (1) Supported in part by the United States Public Health Service JULIVS AXELROD and t h e Eugene Higgins Trust. NATIONAL HEARTIWSTITCTE U. S. DEPARTMENT OF HEALTH, ELIZABETH S. MAXWELL (2) T. D. Fontaine, J. S. Ard and R. hl. Ma, THISJ O U K N A L ~ 7 3 , 878 (1951). AND WELFARE EDUCATION, (3) Y.Sato, A. Katz and E. Mosettig, i b i d . , 7 3 , 880 (39913. BETHESDA, MARYLAND (4) R. K u h n and I. Low, Bcr., 85, 416 (1962). RECEIVED KOVEMBER 10, 1954
AND
( 5 ) F. C. Uhle, THISJOURNAL,76, 2280 (1953)
(8) Visiting Scientist of the National Institutes 01 Health on leave o f absence from the Institute of Cytoghysiology, University of Copenhaxeo.
(6) F.C . Uhle. i b i d . , 7 6 , 4245 (1954). ( 7 ) I . Schcer, R. B. Kostic and R M
