TABLE 3.
Acceptor specificity of ATasea
| Acceptor substrates of the ATaseb | Specificity valvesc
|
|
|---|---|---|
| TLC | HPLC (%) | |
| Nonyl-α-d-glucopyranoside | + | 28.1 |
| Xylobiose | + | 20.8 |
| Maltotetraose | + | 19.9 |
| Maltotriose | + | 19.8 |
| Maltoheptaose | + | 18.9 |
| Maltopentaose | + | 17.9 |
| Cellobiose | − | 17.2 |
| Maltohexaose | + | 17.2 |
| Octyl-α-d-maltopyranoside | + | 16.5 |
| Laminaribiose | + | 16.3 |
| Sophorose | + | 16.3 |
| Decyl-α-d-maltopyranoside | + | 16.2 |
| d-(−)-Salicin | + | 14.8 |
| Phenyl-α-d-glucopyranoside | + | 14.8 |
| Panose | + | 14.0 |
| Octyl-d-glucopyranoside | + | 14.0 |
| Methyl-α-d-Glucopyranoside | + | 11.5 |
| l-(−)-Xylose | + | 11.0 |
| Dextrin | + | 10.0 |
| Isomaltose | + | 9.7 |
| Palatinose | − | 9.3 |
| Nigerose | + | 8.8 |
| 4-Nitrophenyl-α-d-glucopyranoside | + | 8.5 |
| d-(+)-Glucose | + | 7.6 |
| d-(+)-Xylose | + | 5.7 |
| Isomaltotriose | + | 5.4 |
| α-d-(+)-Maltose-1-phosphate | + | 5.2 |
| 6-Deoxy-glucose | + | 4.9 |
| l-(−)-Glucose | + | 4.7 |
| 5-Thio-d-glucose | + | 4.4 |
| d-(−)-Gluconolactone | + | 3.7 |
| myo-Inosit | + | 3.2 |
| Maltitol | + | 3.0 |
| Amygdalin | + | |
| Amylopektin | + | |
| 4-Nitrophenyl-α-d-xylopyranoside | + | |
The various substrates (each at 23 mM) were incubated with acarbose (23 mM) and purified ATase (15 nkat/ml) in 0.1 mM Tris-HCl buffer (pH 7.2) plus 0.01 mM CaCl2 for 18 h.
No formation of maltose and of new compounds was measured (via TLC and/or HPLC) for the following substrates: l-arabinose (TLC, HPLC), d-arabinose (TLC, HPLC), d-lyxose (TLC, HPLC), d-ribose (TLC, HPLC), 1.6-anhydro-d-glucose (TLC, HPLC), N-acetyglucosamine (TLC, HPLC), 2-deoxy-d-glucose (TLC, HPLC), d-(−)-fructose (TLC, HPLC), l-(−)-fucose (TLC, HPLC), d-(+)-galactose (TLC, HPLC), glucosamine (TLC, HPLC), d-glucuronic acid (TLC, HPLC), α-d-glucose-6-phosphate (TLC, HPLC), 3-O-methyl-α-glucopyranoside (TLC), d-(+)-mannose (TLC, HPLC), lactose (HPLC), melibiose (HPLC), saccharose (HPLC), trehalose (HPLC), turanose (HPLC), melezitose (HPLC), raffinose (HPLC), cyclo-α-dextrin (TLC, HPLC), and valienamin (TLC).
Product formation was determined by HPLC (i.e., the relative percent signal intensity of the maltose peak [100% = the sum of all recorded peaks]) or by TLC (“+” [formation of maltose and a new compound detected by TLC] or “−” [no maltose formation]).