Metabolic ¹³C-Labeling of An Antitumor (1→3)-β-D-Glucan, SSG, from Sclerotinia sclerotiorum IFO 9395

Abstract

A (1→3)-β-D-glucan, SSG, from Sclerotinia sclerotiorum IFO 9395 was metabolically labeled using [1-¹³C] and [2-¹³C]glucose, and the fate of the ¹³C-label was examined by ¹³C-NMR spectroscopy. ¹³C-NMR spectra of metabolically labeled SSG (¹³C-SSG) showed that most of the ¹³C-label in glucose residues of ¹³C-SSG were recovered from the originally labeled sites of carbon in glucose residue, and suggested little rearrangement during take-up from the medium. In the case of poor SSG producing culture conditions (reduced shaking rate), ¹³C-glucose incorporation in SSG molecule was similar to that in the case of high SSG-producing culture conditions. In addition, significant amounts of ¹³C-labeled trehalose were found in ¹³C-NMR spectra of the mycelium cultured in both poor and high SSG-producing conditions. These results suggested that different culture conditions affected SSG production, but not the metabolism of glucose and the biosynthetic pathway of SSG.