Results And Discussion

Experimental data were collected under seven kinds of steady state conditions (Table 1); residual glutamine concentration was constant and residual glucose concentration was changed (a-e), and residual glutamine concentration was constant and residual glutamine concentration was changed (a, f, and g).

a

b

c

d

e

f

g

glucose

feed

23.20

11.80

7.65

2.35

1.14

23.55

23.45

residual

12.10

0.46

0.23

0.03

0.01

9.83

13.75

glutamine ■

feed

6.92

8.00

6.72

7.09

7.96

3.56

0.11

residual

3.14

2.08

2.68

1.91

2.00

0.29

0.00

Figure 1(a) shows that specific rates of glucose uptake and lactate production increase with residual glucose up to 0.5 mM. They are constant more than 0.5 mM of residual glucose. Specific rates of glutamine uptake and ammonia production decrease with residual glucose up to 0.05 mM. They are constant more than 0.05 mM of residual glucose. Figure 1(b) shows that specific rates of glucose uptake and lactate production decrease with residual glutamine. However, specific rates of glutamine uptake and ammonia production are constant in high residual glutamine ( Cgin > 0.4 mM ). Figure 2(a) and 2(b) show specific mAb production rates. There are no residual glucose dependency changes of specific mAb production rate. However specific mAb production rate is influenced by residual glutamine concentration. It is rather higher in low glutamine concentration.

residual glutamine [mM|

Figure 1. (a) Glucose, and (b) glutamine dependency changes of specific rates residual glutamine [mM|

Figure 1. (a) Glucose, and (b) glutamine dependency changes of specific rates

Figure 2. (a) Glucose, and (b) Glutamine dependency mAb production rate

Intracellular fluxes were estimated from extracellular utilization and production rates. Figure 3(a) shows that flux profile of glucose to pyruvate is as same as that of pyruvate to lactate. Up to 0.4 mM of residual glucose, fluxes of glucose to pyruvate and pyruvate to lactate increase with residual glucose. More than 4 mM of glucose these two fluxes are constant. The flux of pyruvate to acetyl-CoA does not influenced on residual glucose. All fluxes as shown in figure 3(b) decrease according to increase of residual glutamine. Figure 4(a) shows that there is no residual glucose concentration dependency changes of the TCA related fluxes. The TCA related fluxes decrease with increase of residual glutamine as shown in figure 4(b). Figure 5(a) shows that glutamine flux to glutamic acid does not change in the experimental range and glutamic acid flux to a-keto glutalate decreases according to residual glutamine and almost zero more than 0.2 mM glutamine. Figure 5(b) shows that these two fluxes show the same profile. In high glutamine (>0.5 mM) they are not influenced by glutamine concentration, in low glutamine they converge to zero.

residual glucose [mM]

residual glucose [mM]

residual glutamine [mM]

Figure 3. Estimated glycolysis related metabolic fluxes (a) glucose, and (b) glutamine dependency changes

residual glutamine [mM]

Figure 3. Estimated glycolysis related metabolic fluxes (a) glucose, and (b) glutamine dependency changes

Figure 4. Estimated the TCA cycle related metabolic fluxes (a) glucose, and (b) glutamine dependency changes
Figure 5. Estimated glutaminolysis related metabolic fluxes (a) glucose, and (b) glutamine dependency changes
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