|
H2O2 in feed (mM)
|
H2O2 feed rate (µM h−1)
|
LPMO activitya, 1 h (min−1)
|
Cumulative [H2O2] after 6 h (µM)b
|
[Glc4gemGlc] after 6 h (µM)
|
[Product]/[H2O2] ratio after 6 h (%)c
|
LPMO activitya, 6 h (min−1)
|
|---|
|
45
|
30
|
0.29
|
180
|
161.5
|
89.7
|
0.22
|
|
135
|
90
|
0.63
|
540
|
444.4
|
82.3
|
0.62
|
|
270
|
180
|
1.25
|
1080
|
947.5
|
87.7
|
1.32
|
|
450
|
300
|
2.02
|
1800
|
1394.2
|
77.5
|
1.94
|
|
900
|
600
|
4.13
|
3600
|
3018.2
|
83.8
|
4.19
|
|
4500
|
3000
|
15.05
|
18,000
|
2004.7
|
11.1
|
2.78
|
- aApparent LPMO turnover rates were calculated based on the assumption that 15% (w/w) of the proteins in Cellic® CTec2 is composed of LPMOs [16]. Avicel (10% w/w DM) was hydrolyzed with Cellic® CTec2 (4 mg protein/g DM), yielding a total protein concentration of 400 mg L−1, whereof LPMOs constitute 60 mg L−1, which equals 2 µM (using a molecular weight of 30,000 g mol−1). Turnover rates were estimated from the 1 and the 6 h points shown in Fig. 3a. Comparison of the 1 and 6 h rates shows that product formation was almost linear with time in these 6 h, except for the highest feed rate; see also Fig. 3a. Reactions were carried out in sodium acetate buffer (pH 5.0, 50 mM) at 50 °C, under stirring and continuous nitrogen sparging, using AscA (1 mM) as reductant
- bH2O2 concentration that would be measured in the bioreactor if added H2O2 would accumulate, assuming that nothing is consumed or produced by the LPMOs or by redox side reactions with AscA
- cThis column lists the Glc4gemGlc concentration as percentage of the cumulative hypothetical H2O2 concentration (see footnote b), after 6 h reaction. In the presence of cellulases, as in Cellic® CTec2, all C4-oxidized products are converted to Glc4gemGlc, and C1-oxidized products to gluconic acid and cellobionic acid. See text for more details
