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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 +Σ 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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BMC Systems Biology

ISSN: 1752-0509

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