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The following reaction leading to the synthesis of the trisaccharide umbelliferose was demonstrated in an enzyme preparation from leaves of Aegopodium podagraria L.: sucrose + UDP-gal-'4C -e umbelliferose-'4C + UDP. Neither galactinol nor galactose 1-phosphate could replace UDP-gal. Among 10 different sugars tested only sucrose was a suitable galatosyl acceptor. The trisaccharide umbelliferose (O-a-D-galactopyranosyl-(l-2)-O-a-D-glucopyranosyl-(1 -2)-O-,8-D-fructofuranoside) wasfound and identified by Wickstrom and Svendsen (9). Although it is very widespread within the umbelliferes (1, 2, 7), its biosynthesis is hitherto unknown. Since raffinose, another much more widespread galactoside of sucrose, is formed by a transfer reaction in which galactinol is the galactosyl donor (4), we studied the occurrence of galactinol in umbellifers. Only traces of galactinol could be found in such leaves, which also contained very small amounts of raffinose in addition to umbelliferose. No correlation between the occurrence of umbelliferose and galactinol could be found, however (3). Also no other unusual galactoside which could serve as galactosyldonor was detected in labeling experiments similar to the studies of Senser and Kandler (6). It was, therefore, suggested that the galactosyldonor in the biosynthesis of umbelliferose may be a nucleotide-activated galactose or galactose 1-phosphate, both present in leaves of umbellifers. This paper describes an enzyme preparation from the leaves of Aegopodium podagraria which transfers galactose specifically from UDP-gal to position 2 of sucrose, yielding umbelliferose. MATERIALS AND METHODSThe enzyme was prepared as follows. Fifteen g of fully expanded leaves of Aegopodium podagraria L. grown in the open air were frozen in liquid nitrogen and ground in a mortar.After mixing with the same weight of polyvinylpyrrolidone (5), the powder was extracted in the cold with 100 ml of 0.1 M tris-HCl-buffer (pH 7.0) containing 10 mm dithioerythritol. Sucrose-'4C and UDP-gal-"4C were purchased from Amersham (England), labeled raffinose and umbelliferose were isolated from leaves of Lamium maculatum and Aegopodium podagraria, respectively, after the leaves were allowed to photosynthesize in "4CO2 for several hours (6). Paper electrophoresis was carried out in 0.05 M sodiumtetraborate, pH 9.8, and in 0.1 M ammonia formate, pH 3.7. The radioactive areas were located by autoradiography. The radioactivity was measured directly on paper with a methane flow counter Frieseke and Hoepfner 407 A. RESULTS AND DISCUSSION To demonstrate the synthesis of umbelliferose from sucrose and various galactosyldonors, as well as the exchange reaction between umbelliferose and sucrose, the combinations of labeled and unlabeled acceptors and donors listed in Table 1 were used. Only in assays No. 2 and 3 labeled umbelliferose could be found on the one-dimensional chromatogram (solvent III). Unlike the results of similar experiments on raffinose (5) and stachyose biosynthesis (8), no exchange reaction could b...

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