Figure 2.

Representative in vitro ¹³C-NMR spectra (scale from 10–110 ppm) of sycamore cells (perchloric extract). The spectra, recorded at 20°C, are the results of 900 transients (90 min). Perchloric extracts were prepared from a standard exponentially growing suspension culture (9 g wet weight) according to the procedure described in “Materials and Methods.” A, Control cells at pH 6.0; B, cells incubated for 2 d with 5 mm [¹³C]methanol at pH 6.0. Note that the C-3 resonance of Ser is well separated from the resonance of the methyl group of methyl-β-d-glucopyranoside (compare with Fig. 1). The resonance frequency associated with methanol was not observed in the perchloric extract (compare with Fig. 1, for an explanation see text). Inset, 0050 Expanded scale (magnification, ×20) from 103.75 to 104.75 ppm showing the C-1 resonance of methyl-β-d-glucopyranoside (this resonance appeared as two distinct peaks, for an explanation see text). The ¹³C-enrichment at the methyl position of methyl-β-d-glucopyranoside was found to be 100%. Part of the amino acid and organic acid methylene groups are shown on expanded scales (magnification, ×8). Peak assignments are as follows: MeG, [¹³C]methyl-β-d-glucopyranoside; cit, citrate; mal, malate; suc, succinate; Glu, Glu; Met, [¹³CH₃]Met; S, Suc.