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Table 1 Measured and simulated fractions of isotopologues and total concentrations of metabolites.

From: Compartmentation of glycogen metabolism revealed from 13C isotopologue distributions

  Experiment Simulated
  mean sd Channeling Mixed
Glucose   χ 2 = 0.442 0.406
m0 0.512 ± 0.0069 0.511 0.511
m1 0.00913 ± 0.002 0.0084 0.00839
m2 0.478 ± 0.00652 0.481 0.481
[mM] 19.7 ± 1.92 20.4 20.2
Lactate χ 2 = 1.43 7.32
m0 0.86 ± 0.0482 0.839 0.81
m1 0.0235 ± 0.00802 0.0237 0.0178
m2 0.0946 ± 0.0388 0.133 0.17
m3 0.022 ± 0.0438 0.00381 0.00145
[mM] 0.81 ± 0.51 0.959 1.48
Glutamate C2-C5 χ 2 = 0.0564 0.0424
m0 0.912 ± 0.0343 0.912 0.912
m1 0.0299 ± 0.0116 0.0301 0.0298
m2 0.0523 ± 0.0217 0.0574 0.0567
Glutamate C2-C4 χ 2 = 0.0049 0.00437
m0 0.919 ± 0.0339 0.919 0.919
m1 0.0365 ± 0.00175 0.0356 0.355
m2 0.0446 ± 0.0166 0.0454 0.0451
Glycogen χ 2 = 1.2 30.5
m0 0.608 ± 0.0388 0.598 0.658
m1 0.0162 ± 0.0033 0.0151 0.0271
m2 0.362 ± 0.0351 0.375 0.299
m3 0.00399 ± 0.0011 0.00422 0.00791
m4 0.00961 ± 0.0026 0.00748 0.00749
m5 0.000464 ± 0.00016 0.000432 0.000533
mg/mL 0.355 ± 0.112 0.313 0.232
Σ 1 χ 2 3.13 38.28
Glycogen C1-C4 χ 2 = 1.42 6.68
m0 0.613 ± 0.0448 0.627 0.679
m1 0.0224 ± 0.00834 0.0133 0.0297
m2 0.357 ± 0.0425 0.358 0.289
Glycogen C3-C6 χ 2 = 7.97 30
m0 0.952 ± 0.00767 0.952 0.951
m1 0.00743 ± 0.00211 0.0131 0.018
m2 0.0371 ± 0.00467 0.0333 0.0279
Σ 2 χ 2 9.21 36.68
Σ t χ 2 = Σ 1 χ 2 2 χ 2 12.52 74.95
  1. Isotopologues (m0, non-labeled; m1, containing one 13C isotope; m2, two 13C isotopes, etc) produced by isolated hepatocytes from glucose as the only substrate contained 50% of [1,2-13C2]D-glucose were measured in glucose from medium, glucose from glycogen and its fragments, lactate, and fragments of glutamate after two hours of incubation. The measurements are presented as mean ± standard deviation. The data were simulated using two models that either accounted for channeling or suggested a single "mixed" pool of hexose phosphates in accordance with the schemes presented in Figure 1. The fitting was performed using a stochastic algorithm described in Methods. The difference between the best fit and experimental data (χ2, see Methods) are shown for each metabolite and summarized for the whole set of data.
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