Figure 8.

Isotopic analysis of the de novo and salvage pathway contributions to mannose metabolism. Samples of sVSG from cells grown in 5 mM [U-¹³C]-d-Glc under different conditions were subjected to acid hydrolysis and their Man and Gal contents were analysed as TMS-derivatives by GC-MS. The relative percentages of the ¹²C- and ¹³C-variants of Man and Gal were determined from their electron impact spectra and the results of triplicate analyses (mean ± standard deviation) are shown. In the absence of any additions, about 95% of the Man and Gal was shown to be ¹³C-labelled. However, in the presence of 55 µM Man, the proportion of ¹³C-labelled Man reduced to 75% while Gal was unaffected. In the presence of 1.5 mM Man, the proportion of ¹³C-labelled Man was further reduced to 10% and the proportion of ¹³C-labelled Gal was reduced to 80%.