Test ID: ADA
Adenosine Deaminase, Blood
Method Description 
Describes how the test is performed and provides a method-specific reference
The ADA assay is also based on the enzymatic deamination of adenosine to inosine. Inosine is converted to hypoxanthine by purine nucleoside phosphorylase (PNP). Hypoxanthine is then converted to uric acid and hydrogen peroxide (H2O2) by xanthine oxidase (XOD). H2O2 is further reacted with N-Ethyl-N-(2-hydroxy-3-sulfopropyl)-3-methylaniline (EHSPT) and 4-aminoantipyrine (4-AA) in the presence of peroxidase (POD) to generate quinone dye which is monitored in a kinetic manner. The entire enzymatic reaction scheme is shown below.
|
| ADA |
|
| adenosine + H2O | -----> | inosine + NH3 |
|
| PNP |
|
| inosine + Pi | -----> | hypoxanthine + ribose-1-phosphate |
|
| XOD |
|
| hypoxanthine + 2H2O + 2O2 | -----> | uric acid + 2H2O2 |
|
| POD |
|
| 4H2O2 + 4-AA + EHSPT | -----> | 4H2O + quinone dye (lamda max 556 nm) |
One unit of ADA is defined as the amount of ADA that generates 1 micromole of inosine from adenosine per minute at 37 degrees C.(Beutler E: Red cell metabolism. In A Manual of Biochemical Methods. Second edition. Grune and Stratton, 1984, pp 99-100)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday
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