Table II.
Hydrolysis of glycosides and oligosaccharides by Os3BGlu6
nd, Not determined.
| Substrate | nmol Glc min−1 mg−1 Proteina | Percent Relative Activitya | Km | kcat | kcat/Km |
|---|---|---|---|---|---|
| mm | s−1 | mm−1 s−1 | |||
| n-Octyl-β-d-glucoside | 2,282 ± 0.9 | 100 ± 0.04 | 4.5 ± 0.3 | 12.4 ± 0.4 | 2.7 |
| n-Heptyl-β-d-glucoside | 673.8 ± 0.9 | 29.5 ± 0.04 | 5.0 ± 0.3 | 4.25 ± 0.10 | 0.85 |
| Glucooligosaccharides | |||||
| Laminaribiose [β-(1→3)-linked] | 1,272 ± 1.3 | 55.7 ± 0.05 | 3.6 ± 0.3 | 6.17 ± 0.19 | 1.7 |
| Laminaritriose | 169.6 ± 0.9 | 7.43 ± 0.04 | 8.7 ± 0.7 | 1.64 ± 0.06 | 0.18 |
| Laminaritetraose | 2.0 ± 0.01 | 0.08 ± 0.0004 | nd | nd | nd |
| Laminaripentaose | 1.4 ± 0.01 | 0.06 ± 0.001 | nd | nd | nd |
| Cellobiose [β-(1→4)-linked] | 15.0 ± 0.5 | 0.65 ± 0.001 | 15.3 ± 1.2 | 0.13 ± 0.001 | 0.0085 |
| Cellotriose | 13.1 ± 0.6 | 0.57 ± 0.03 | nd | nd | nd |
| Cellotetraose | 12.9 ± 0.5 | 0.56 ± 0.02 | nd | nd | nd |
| Cellopentaose | 8.0 ± 0.3 | 0.35 ± 0.01 | nd | nd | nd |
| Cellohexaose | 6.38 ± 0.3 | 0.28 ± 0.01 | nd | nd | nd |
| Sophorose [β-(1→2)-linked] | 728.7 ± 1.3 | 31.9 ± 0.05 | 9.8 ± 0.8 | 9.8 ± 0.4 | 0.96 |
| Gentiobiose [β-(1→6)-linked] | 5.25 ± 0.17 | 0.23 ± 0.007 | 14.9 ± 1.1 | 0.17 ± 0.003 | 0.011 |
| Natural β-d-glucosidesb | |||||
| Apigenin-7-glucoside | 15.3 ± 0.2 | 0.66 ± 0.009 | nd | nd | nd |
| Glycitin | 4.4 ± 0.07 | 0.19 ± 0.003 | nd | nd | nd |
| Diadzin | 4.0 ± 0.04 | 0.17 ± 0.001 | nd | nd | nd |
| Genistin | 2.9 ± 0.02 | 0.13 ± 0.001 | nd | nd | nd |
| Esculin | 2.4 ± 0.01 | 0.10 ± 0.005 | nd | nd | nd |
| Arbutin | 0.59 ± 0.05 | 0.02 ± 0.002 | nd | nd | nd |
| Coumaryl alcohol β-d-glucoside | 0.54 ± 0.01 | 0.02 ± 0.0005 | nd | nd | nd |
| Coniferin | 0.46 ± 0.007 | 0.02 ± 0.0003 | nd | nd | nd |
| Salicin | 0.18 ± 0.001 | (79 ± 0.3) × 10−4 | nd | nd | nd |
a
Activities were determined by the Glc oxidase assay, and percent relative rates are set relative to hydrolysis of n-octyl-β-d-glucoside as 100%. Amounts released from disaccharides were divided by two, since two Glc molecules are released from one reaction.
b
The natural glycosides for which relative activities were determined are those for which hydrolysis was detected by TLC. Amygdalin, dalcochinin glucoside, gossypin, linamarin, naringin, phlorizin, prunasin, pyridoxine-5′-O-β-d-glucoside, and quercitin 3-β-d-glucoside were not hydrolyzed, as observed by TLC.