TABLE 4.
Key enzyme activities for pentose utilization in cell extracts of P. putida S12xylAB2 with xylose or arabinose as substratea
| Enzyme | Activity (U g−1) on:
|
|
|---|---|---|
| Xylose | Arabinose | |
| XylA (pentose isomerase) | 34 | 1.5b |
| XylB (“pentulose” kinase) | 134 | NDc |
| XylAB (combined isomerase/kinase) | 22 | 16 |
| Putative C4 epimerased | ND | 194 |
a
ND, not determined.
b
The activity assay of XylA with l-arabinose was compromised by the low affinity of sorbitol dehydrogenase for l-ribulose.
c
The activity of XylB was not determined separately as l-ribulose is not commercially available.
d
The formation of d-xylulose-5-phosphate from l-arabinose was quantified by measuring transketolase activity.