Table 1.
Substrate specificity of recombinant sweetgum LsM88 (CAld5H) and LsCOMT (COMT) proteins and of sweetgum xylem proteins
| Substrate | Substrate specificity (pmol/min per mg protein)
|
|||||
|---|---|---|---|---|---|---|
| Recombinant proteins
|
Xylem proteins
|
|||||
| CAld5H | COMT | CAld5H + COMT | Microsome | Soluble | Microsome + soluble | |
| Coniferyl aldehyde | 723.9 ± 24.0 | 382.2 ± 15.2 | 114.0 ± 3.6 | 13.8 ± 1.2 | ||
| (5-OH-CAld) | (SAld) | (5-OH-CAld) | (SAld) | |||
| Ferulate | 60.7 ± 3.2 | 32.2 ± 2.4 | 26.3 ± 1.2 | 12.0 ± 1.4 | ||
| (5-OH-FA) | (SA) | (5-OH-FA) | (SA) | |||
| 5-Hydroxyconiferyl aldehyde | 14,370 ± 200 | 5,900 ± 35 | ||||
| (SAld) | (SAld) | |||||
| 5-Hydroxyferulate | 12,710 ± 70 | 5,700 ± 90 | ||||
| (SA) | (SA) | |||||
| 526.5 ± 30.0 | 247.5 ± 17.2 | 8.8 ± 1.4 | 4.8 ± 1.9 | |||
| Coniferyl aldehyde + ferulate | (5-OH-CAld) | (SAld) | (5-OH-CAld) | (SAld) | ||
| 0 | 0 | 0 | 0 | |||
| (5-OH-FA) | (SA) | (5-OH-FA) | (SA) | |||
Substrate and recombinant protein concentrations and the control experiments were the same as described in Fig. 2. For assaying xylem proteins, 9.5 and 720 μg of soluble and microsome proteins were used, respectively, with the same substrate concentrations as for recombinant proteins and boiled plant proteins as control. Specific activities were mean ± SD (n = two to three independent assays). Reaction products: 5-OH-CAld, 5-hydroxyconiferyl aldehyde; 5-OH-FA, 5-hydroxyferulate; SAld, sinapyl aldehyde; SA, sinapate.