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Table 3 Enzyme activities and kinetic properties

From: Xylose reductase from Pichia stipitis with altered coenzyme preference improves ethanolic xylose fermentation by recombinant Saccharomyces cerevisiae

Strain XR gene Cofactor Specific XR activity U mg-1 protein KmA μM KmB mM KiA μM Vmax U mg-1 protein
Y-PsNative XYL1 NADPH
NADH
0.23 ± 0.06
0.10 ± 0.02
1.0 ± 0.6
28.7 ± 5.4
62.2 ± 27.7
59.2 ± 10.5
1.4 ± 1.2
25.9 ± 11.7
0.30 ± 0.05
0.21 ± 0.01
Y-PsK270M XYL1(K270M) NADPH
NADH
0.08 ± 0.01
0.04 ± 0.01
290 ± 78.6
-
454 ± 142
-
293 ± 169
-
0.91 ± 0.09
-
Y-PsK270R XYL1(K270R) NADPH
NADH
0.54 ± 0.02
0.32 ± 0.02
25.8 ± 9.1
62.8 ± 18.7
468 ± 151
145 ± 36.9
22.9 ± 17.6
57.4 ± 34.9
2.13 ± 0.24
0.96 ± 0.09
Y-CpXR XYL1(C. parapsilosis) NADPH
NADH
n.d.
n.d.
-
-
-
-
-
-
-
-
  1. Specific XR activity in cell extracts from strains Y-PsNative, Y-PsK270M, Y-PsK270R and Y-CpXR in standard conditions (200 μM NAD(P)H, 350 mM xylose) and estimated kinetic parameters for NAD(P)H reduction of xylose by corresponding cell extracts. KmA and KmB are the Michaelis constants of NAD(P)H and xylose, respectively, KiA is the dissociation constant of NAD(P)H and Vmax is the maximum velocity.
  2. n.d. not detected
  3. - not determined