Biosynthesis of D-aldgarose II

Abstract

The incorporation of pyruvate-[2-14C] into the sugars of aldgamycin E in normal fermentations and in resting cell cultures of S. lavendulae was compared. The extent of incorporation of radioactivity into the hydroxyethyl branch of D-aldgarose (3,1′-O-carbo-4,6-dideoxy-3-C-[1′-hydroxyethyl]-D-ribo-hexose) was about the same in both cases (44 - 45% of the radioactivity in aldgarose). With D-glucose-[U-14C] as a precursor the radioactivity was evenly distributed in the hexose chain of aldgarose and D-mycinose (6-deoxy-2,3-O-methyl-D-allose), whereas the incorporation into the hydroxyethyl branch [C-(1′)-C-(2′)] of aldgarose was negligible. Radioactivity from L-ethionine-[ethyl-14C] was not incorporated to a significant extent into C-(1′)-C-(2′) of aldgarose. Experiments with bicarbonate-[14C] indicate that the cyclic carbonate of aldgarose originates from a carboxylation reaction. The results of experiments with oxythiamine, pyrithiamine, bisulfite, and fluoropyruvate did not allow any conclusion on the possible participation of hydroxyethylthiamine-pyrophosphate in the biosynthesis of aldgarose.