TABLE 2
FROM:
Radiolabeled Cholinesterase Substrates:In Vitro Methods for Determining Structure-Activity Relationships and Identification of a Positron Emission Tomography Radiopharmaceutical for In Vivo Measurement of Butyrylcholinesterase Activity
Scott E Snyder, Neeraja Gunupudi, Phillip S Sherman, Elizabeth R Butch, Marc B Skaddan, Michael R Kilbourn, Robert A Koeppe and David E Kuhl
BACK TO ARTICLETable 2. AChE-mediated cleavage rates for ChE substrates
| Substrate* | [AChE]† (U/mL) | Rate ( A/min/U/L)‡
| Relative rate (AMP = 100)§ |
|---|---|---|---|
| ACh | 1 | -1.45  0.09 | |
| 2 | -1.33 0.03 | n.d. | |
| BCh | 100 | (0)
| n.d. |
| AMP | 2 | -0.41 0.04 | |
| 10 | -0.394 0.002 | 100.0 0.5 | |
| PMP | 10 | -0.079 0.001 | 20.0 0.3 |
| iBMP | 20 | (0)
| |
| 100 | -0.0102 0.0003 | 2.6 0.1 | |
| nBMP | 100 | (0)
| 0 |
* Substrate abbreviations as per Table 1. Substrate concentration = 50 mg/mL.
† Enzyme concentrations are indicated in enzymatic units per milliliter (U/mL).
‡ Cleavage rates measured as the change in m-nitrophenol absorbance (420 nm) per minute per unit of enzyme per liter (A/min/U/L) and expressed as mean SD for n 
3 assays.
§ Rates expressed relative to AMP = 100.
Change in absorbance was below the assay accuracy limit of A = 0.05 within 120 minutes (Rappaport, 1959) or <0.004 A/min/U/L.
