TABLE 3.
Substrate specificity of EstAa
| Side chain length (no. of C atoms) | Activityb on:
|
|||
|---|---|---|---|---|
| α-Naphthyl ester | β-Naphthyl ester | HPTS substrates | Triglyceride | |
| 2 | ++ | +++ | − | ND |
| 3 | ++ | +++ | ND | ND |
| 4 | ++ | +++ | − | + |
| 5 | ND | ++ | ND | ND |
| 6 | + | + | ND | + |
| 8 | ND | ND | + | ND |
| 9 | − | ND | + | ND |
| 10 | ND | ND | ND | + |
| 12 | − | ND | ++ | +/− |
| 14 | − | ND | ND | − |
| 16 | − | ND | ND | ND |
| 18 | ND | ND | +++ | − |
a
The ability of EstA to hydrolyze various chromatogenic and fluorogenic substrates was tested with the aid of qualitative colorimetric assays and by staining of native polyacrylamide gels as described in Materials and Methods. Membrane protein fractions of E. coli BL21(pTO-estA) were used for these assays.
b
+++, strong activity; ++, moderate activity; +, weak activity; −, no activity, ND, not determined.