TABLE 3.
Determination of debranching enzyme activity
Protein extracts of wild-type, isa3lda, amy3isa3lda, isa1isa2isa3lda, and amy3isa1isa2isa3lda plants were tested for their debranching activity as described under “Experimental Procedures.” Maltose and maltotriose were determined using HPAEC-PAD. Maltose levels reflect the combination of debranching activity and β-amylolytic activity, whereas maltotriose reflects primarily debranching enzyme activity. The values of the two independent experiments (Experiments 1 and 2) are means of two technical replicates from extracts of four plants pooled prior to extraction. The amounts of maltose and maltotriose liberated were set to 100% for wild-type extracts.
| Genotype of plants | Experiment 1 |
Experiment 2 |
||
|---|---|---|---|---|
| Maltose released | Maltotriose released | Maltose released | Maltotriose released | |
| % | % | % | % | |
| Wild type | 100.0 | 100.0 | 100.0 | 100.0 |
| isa3lda | 14.9 | 3.5 | 23.6 | 2.7 |
| amy3isa3lda | 11.4 | 3.0 | 20.9 | 2.2 |
| isa1isa2isa3lda | 15.5 | 1.6 | 47.6 | −0.6 |
| amy3isa1isa2isa3lda | 16.0 | 1.8 | 24.8 | 0.5 |